Class Algorithms

Algorithms contains a number of static methods that implement algorithms that work on collections. Most of the methods deal with the standard generic collection interfaces such as IEnumerable<T>, ICollection<T> and IList<T>.

Inheritance

System.Object

Algorithms

Inherited Members

System.Object.Equals(System.Object)

System.Object.Equals(System.Object, System.Object)

System.Object.GetHashCode()

System.Object.GetType()

System.Object.MemberwiseClone()

System.Object.ReferenceEquals(System.Object, System.Object)

System.Object.ToString()

Namespace: Wintellect.PowerCollections

Assembly: CADability.dll

Syntax

public static class Algorithms

Methods

BinarySearch<T>(IList<T>, T, IComparer<T>, out Int32)

Searches a sorted list for an item via binary search. The list must be sorted by the ordering in the passed instance of IComparer<T>.

Declaration

public static int BinarySearch<T>(IList<T> list, T item, IComparer<T> comparer, out int index)

Parameters

Type	Name	Description
System.Collections.Generic.IList<T>	list	The sorted list to search.
T	item	The item to search for.
System.Collections.Generic.IComparer<T>	comparer	The comparer instance used to sort the list. Only the Compare method is used.
System.Int32	index	Returns the first index at which the item can be found. If the return value is zero, indicating that item was not present in the list, then this returns the index at which item could be inserted to maintain the sorted order of the list.

Returns

Type	Description
System.Int32	The number of items equal to item that appear in the list.

Type Parameters

Name	Description
T

BinarySearch<T>(IList<T>, T, Comparison<T>, out Int32)

Searches a sorted list for an item via binary search. The list must be sorted by the ordering in the passed Comparison<T> delegate.

Declaration

public static int BinarySearch<T>(IList<T> list, T item, Comparison<T> comparison, out int index)

Parameters

Type	Name	Description
System.Collections.Generic.IList<T>	list	The sorted list to search.
T	item	The item to search for.
System.Comparison<T>	comparison	The comparison delegate used to sort the list.
System.Int32	index	Returns the first index at which the item can be found. If the return value is zero, indicating that item was not present in the list, then this returns the index at which item could be inserted to maintain the sorted order of the list.

Returns

Type	Description
System.Int32	The number of items equal to item that appear in the list.

Type Parameters

Name	Description
T

BinarySearch<T>(IList<T>, T, out Int32)

Searches a sorted list for an item via binary search. The list must be sorted by the natural ordering of the type (it's implementation of IComparable<T>).

Declaration

public static int BinarySearch<T>(IList<T> list, T item, out int index)
    where T : IComparable<T>

Parameters

Type	Name	Description
System.Collections.Generic.IList<T>	list	The sorted list to search.
T	item	The item to search for.
System.Int32	index	Returns the first index at which the item can be found. If the return value is zero, indicating that item was not present in the list, then this returns the index at which item could be inserted to maintain the sorted order of the list.

Returns

Type	Description
System.Int32	The number of items equal to item that appear in the list.

Type Parameters

Name	Description
T

CartesianProduct<TFirst, TSecond>(IEnumerable<TFirst>, IEnumerable<TSecond>)

Computes the cartestian product of two collections: all possible pairs of items, with the first item taken from the first collection and the second item taken from the second collection. If the first collection has N items, and the second collection has M items, the cartesian product will have N * M pairs.

Declaration

public static IEnumerable<Pair<TFirst, TSecond>> CartesianProduct<TFirst, TSecond>(IEnumerable<TFirst> first, IEnumerable<TSecond> second)

Parameters

Type	Name	Description
System.Collections.Generic.IEnumerable<TFirst>	first	The first collection.
System.Collections.Generic.IEnumerable<TSecond>	second	The second collection.

Returns

Type	Description
System.Collections.Generic.IEnumerable<Pair<TFirst, TSecond>>	An IEnumerable<Pair<TFirst, TSecond>> that enumerates the cartesian product of the two collections.

Type Parameters

Name	Description
TFirst	The type of items in the first collection.
TSecond	The type of items in the second collection.

Concatenate<T>(IEnumerable<T>[])

Concatenates all the items from several collections. The collections need not be of the same type, but must have the same item type.

Declaration

public static IEnumerable<T> Concatenate<T>(params IEnumerable<T>[] collections)

Parameters

Type	Name	Description
System.Collections.Generic.IEnumerable<T>[]	collections	The set of collections to concatenate. In many languages, this parameter can be specified as several individual parameters.

Returns

Type	Description
System.Collections.Generic.IEnumerable<T>	An IEnumerable that enumerates all the items in each of the collections, in order.

Type Parameters

Name	Description
T

Convert<TSource, TDest>(IEnumerable<TSource>, Converter<TSource, TDest>)

Convert a collection of items by applying a delegate to each item in the collection. The resulting collection contains the result of applying converter to each item in sourceCollection, in order.

Declaration

public static IEnumerable<TDest> Convert<TSource, TDest>(IEnumerable<TSource> sourceCollection, Converter<TSource, TDest> converter)

Parameters

Type	Name	Description
System.Collections.Generic.IEnumerable<TSource>	sourceCollection	The collection of item being converted.
System.Converter<TSource, TDest>	converter	A delegate to the method to call, passing each item in sourceCollection.

Returns

Type	Description
System.Collections.Generic.IEnumerable<TDest>	The resulting collection from applying converter to each item in sourceCollection, in order.

Type Parameters

Name	Description
TSource	The type of items in the collection to convert.
TDest	The type each item is being converted to.

Exceptions

Type	Condition
System.ArgumentNullException	sourceCollection or converter is null.

Copy<T>(IEnumerable<T>, T[], Int32)

Copies all of the items from the collection source to the array dest, starting at the index destIndex.

Declaration

public static void Copy<T>(IEnumerable<T> source, T[] dest, int destIndex)

Parameters

Type	Name	Description
System.Collections.Generic.IEnumerable<T>	source	The collection that provide the source items.
T[]	dest	The array to store the items into.
System.Int32	destIndex	The index to begin copying items to.

Type Parameters

Name	Description
T

Exceptions

Type	Condition
System.ArgumentOutOfRangeException	destIndex is negative or greater than dest.Length.
System.ArgumentNullException	source or dest is null.
System.ArgumentException	The collection has more items than will fit into the array. In this case, the array has been filled with as many items as fit before the exception is thrown.

Copy<T>(IEnumerable<T>, T[], Int32, Int32)

Copies at most count items from the collection source to the array dest, starting at the index destIndex. The source collection must not be the destination array or part thereof.

Declaration

public static void Copy<T>(IEnumerable<T> source, T[] dest, int destIndex, int count)

Parameters

Type	Name	Description
System.Collections.Generic.IEnumerable<T>	source	The collection that provide the source items.
T[]	dest	The array to store the items into.
System.Int32	destIndex	The index to begin copying items to.
System.Int32	count	The maximum number of items to copy. The array must be large enought to fit this number of items.

Type Parameters

Name	Description
T

Exceptions

Type	Condition
System.ArgumentOutOfRangeException	destIndex is negative or greater than dest.Length.
System.ArgumentOutOfRangeException	count is negative or destIndex + count is greater than dest.Length.
System.ArgumentNullException	source or dest is null.

Copy<T>(IEnumerable<T>, IList<T>, Int32)

Copies all of the items from the collection source to the list dest, starting at the index destIndex. If necessary, the size of the destination list is expanded.

Declaration

public static void Copy<T>(IEnumerable<T> source, IList<T> dest, int destIndex)

Parameters

Type	Name	Description
System.Collections.Generic.IEnumerable<T>	source	The collection that provide the source items.
System.Collections.Generic.IList<T>	dest	The list to store the items into.
System.Int32	destIndex	The index to begin copying items to.

Type Parameters

Name	Description
T

Exceptions

Type	Condition
System.ArgumentOutOfRangeException	destIndex is negative or greater than dest.Count.
System.ArgumentNullException	source or dest is null.

Copy<T>(IEnumerable<T>, IList<T>, Int32, Int32)

Copies at most count items from the collection source to the list dest, starting at the index destIndex. If necessary, the size of the destination list is expanded. The source collection must not be the destination list or part thereof.

Declaration

public static void Copy<T>(IEnumerable<T> source, IList<T> dest, int destIndex, int count)

Parameters

Type	Name	Description
System.Collections.Generic.IEnumerable<T>	source	The collection that provide the source items.
System.Collections.Generic.IList<T>	dest	The list to store the items into.
System.Int32	destIndex	The index to begin copying items to.
System.Int32	count	The maximum number of items to copy.

Type Parameters

Name	Description
T

Exceptions

Type	Condition
System.ArgumentOutOfRangeException	destIndex is negative or greater than dest.Count
System.ArgumentOutOfRangeException	count is negative.
System.ArgumentNullException	source or dest is null.

Copy<T>(IList<T>, Int32, T[], Int32, Int32)

Copies count items from the list or array source, starting at the index sourceIndex, to the array dest, starting at the index destIndex. The source may be the same as the destination array.

Declaration

public static void Copy<T>(IList<T> source, int sourceIndex, T[] dest, int destIndex, int count)

Parameters

Type	Name	Description
System.Collections.Generic.IList<T>	source	The list or array that provide the source items.
System.Int32	sourceIndex	The index within sourceto begin copying items from.
T[]	dest	The array to store the items into.
System.Int32	destIndex	The index within destto begin copying items to.
System.Int32	count	The maximum number of items to copy. The destination array must be large enough to hold this many items.

Type Parameters

Name	Description
T

Exceptions

Type	Condition
System.ArgumentOutOfRangeException	sourceIndex is negative or greater than source.Count
System.ArgumentOutOfRangeException	destIndex is negative or greater than dest.Length
System.ArgumentOutOfRangeException	count is negative or too large.
System.ArgumentNullException	source or dest is null.

Copy<T>(IList<T>, Int32, IList<T>, Int32, Int32)

Copies count items from the list source, starting at the index sourceIndex, to the list dest, starting at the index destIndex. If necessary, the size of the destination list is expanded. The source and destination lists may be the same.

Declaration

public static void Copy<T>(IList<T> source, int sourceIndex, IList<T> dest, int destIndex, int count)

Parameters

Type	Name	Description
System.Collections.Generic.IList<T>	source	The collection that provide the source items.
System.Int32	sourceIndex	The index within sourceto begin copying items from.
System.Collections.Generic.IList<T>	dest	The list to store the items into.
System.Int32	destIndex	The index within destto begin copying items to.
System.Int32	count	The maximum number of items to copy.

Type Parameters

Name	Description
T

Exceptions

Type	Condition
System.ArgumentOutOfRangeException	sourceIndex is negative or greater than source.Count
System.ArgumentOutOfRangeException	destIndex is negative or greater than dest.Count
System.ArgumentOutOfRangeException	count is negative or too large.
System.ArgumentNullException	source or dest is null.

Count<T>(IEnumerable<T>)

Count the number of items in an IEnumerable<T> collection. If a more specific collection type is being used, it is more efficient to use the Count property, if one is provided.

Declaration

public static int Count<T>(IEnumerable<T> collection)

Parameters

Type	Name	Description
System.Collections.Generic.IEnumerable<T>	collection	The collection to count items in.

Returns

Type	Description
System.Int32	The number of items in the collection.

Type Parameters

Name	Description
T

Remarks

If the collection implements ICollection<T>, this method simply returns ICollection<T>.Count. Otherwise, it enumerates all items and counts them.

Exceptions

Type	Condition
System.ArgumentNullException	collection is null.

CountEqual<T>(IEnumerable<T>, T)

Counts the number of items in the collection that are equal to find.

Declaration

public static int CountEqual<T>(IEnumerable<T> collection, T find)

Parameters

Type	Name	Description
System.Collections.Generic.IEnumerable<T>	collection	The collection to count items in.
T	find	The item to compare to.

Returns

Type	Description
System.Int32	The number of items in the collection that are equal to find.

Type Parameters

Name	Description
T

Remarks

The default sense of equality for T is used, as defined by T's implementation of IComparable<T>.Equals or object.Equals.

CountEqual<T>(IEnumerable<T>, T, IEqualityComparer<T>)

Counts the number of items in the collection that are equal to find.

Declaration

public static int CountEqual<T>(IEnumerable<T> collection, T find, IEqualityComparer<T> equalityComparer)

Parameters

Type	Name	Description
System.Collections.Generic.IEnumerable<T>	collection	The collection to count items in.
T	find	The item to compare to.
System.Collections.Generic.IEqualityComparer<T>	equalityComparer	The comparer to use to determine if two items are equal. Only the Equals member function will be called.

Returns

Type	Description
System.Int32	The number of items in the collection that are equal to find.

Type Parameters

Name	Description
T

Exceptions

Type	Condition
System.ArgumentException	collection or equalityComparer is null.

CountWhere<T>(IEnumerable<T>, Predicate<T>)

Counts the number of items in the collection that satisfy the condition defined by predicate.

Declaration

public static int CountWhere<T>(IEnumerable<T> collection, Predicate<T> predicate)

Parameters

Type	Name	Description
System.Collections.Generic.IEnumerable<T>	collection	The collection to count items in.
System.Predicate<T>	predicate	A delegate that defines the condition to check for.

Returns

Type	Description
System.Int32	The number of items in the collection that satisfy predicate.

Type Parameters

Name	Description
T

DisjointSets<T>(IEnumerable<T>, IEnumerable<T>)

Determines if two collections are disjoint, considered as sets. Two sets are disjoint if they have no common items.

Declaration

public static bool DisjointSets<T>(IEnumerable<T> collection1, IEnumerable<T> collection2)

Parameters

Type	Name	Description
System.Collections.Generic.IEnumerable<T>	collection1	The first collection.
System.Collections.Generic.IEnumerable<T>	collection2	The second collection.

Returns

Type	Description
System.Boolean	True if collection1 are collection2 are disjoint, considered as sets.

Type Parameters

Name	Description
T

Remarks

The default sense of equality for T is used, as defined by T's implementation of IComparable<T>.Equals or object.Equals.

If both collections are Set, Bag, OrderedSet, or OrderedBag collections, it is more efficient to use the IsDisjoint method on that class.

Exceptions

Type	Condition
System.ArgumentNullException	collection1 or collection2 is null.

DisjointSets<T>(IEnumerable<T>, IEnumerable<T>, IEqualityComparer<T>)

Determines if two collections are disjoint, considered as sets. Two sets are disjoint if they have no common items.

Declaration

public static bool DisjointSets<T>(IEnumerable<T> collection1, IEnumerable<T> collection2, IEqualityComparer<T> equalityComparer)

Parameters

Type	Name	Description
System.Collections.Generic.IEnumerable<T>	collection1	The first collection.
System.Collections.Generic.IEnumerable<T>	collection2	The second collection.
System.Collections.Generic.IEqualityComparer<T>	equalityComparer	The IEqualityComparerComparer<T> used to compare items for equality. Only the Equals and GetHashCode member functions of this interface are called.

Returns

Type	Description
System.Boolean	True if collection1 are collection2 are disjoint, considered as sets.

Type Parameters

Name	Description
T

Remarks

If both collections are Set, Bag, OrderedSet, or OrderedBag collections, it is more efficient to use the IsDisjoint method on that class.

Exceptions

Type	Condition
System.ArgumentNullException	collection1 or collection2 is null.

EqualCollections<T>(IEnumerable<T>, IEnumerable<T>)

Determines if the two collections contain equal items in the same order. The two collections do not need to be of the same type; it is permissible to compare an array and an OrderedBag, for instance.

Declaration

public static bool EqualCollections<T>(IEnumerable<T> collection1, IEnumerable<T> collection2)

Parameters

Type	Name	Description
System.Collections.Generic.IEnumerable<T>	collection1	The first collection to compare.
System.Collections.Generic.IEnumerable<T>	collection2	The second collection to compare.

Returns

Type	Description
System.Boolean	True if the collections have equal items in the same order. If both collections are empty, true is returned.

Type Parameters

Name	Description
T	The type of items in the collections.

Remarks

The default sense of equality for T is used, as defined by T's implementation of IComparable<T>.Equals or object.Equals.

EqualCollections<T>(IEnumerable<T>, IEnumerable<T>, IEqualityComparer<T>)

Determines if the two collections contain equal items in the same order. The passed instance of IEqualityComparer<T> is used for determining if two items are equal.

Declaration

public static bool EqualCollections<T>(IEnumerable<T> collection1, IEnumerable<T> collection2, IEqualityComparer<T> equalityComparer)

Parameters

Type	Name	Description
System.Collections.Generic.IEnumerable<T>	collection1	The first collection to compare.
System.Collections.Generic.IEnumerable<T>	collection2	The second collection to compare.
System.Collections.Generic.IEqualityComparer<T>	equalityComparer	The IEqualityComparer<T> used to compare items for equality. Only the Equals member function of this interface is called.

Returns

Type	Description
System.Boolean	True if the collections have equal items in the same order. If both collections are empty, true is returned.

Type Parameters

Name	Description
T	The type of items in the collections.

Exceptions

Type	Condition
System.ArgumentNullException	collection1, collection2, or equalityComparer is null.

EqualCollections<T>(IEnumerable<T>, IEnumerable<T>, BinaryPredicate<T>)

Determines if the two collections contain "equal" items in the same order. The passed BinaryPredicate is used to determine if two items are "equal".

Declaration

public static bool EqualCollections<T>(IEnumerable<T> collection1, IEnumerable<T> collection2, BinaryPredicate<T> predicate)

Parameters

Type	Name	Description
System.Collections.Generic.IEnumerable<T>	collection1	The first collection to compare.
System.Collections.Generic.IEnumerable<T>	collection2	The second collection to compare.
BinaryPredicate<T>	predicate	The BinaryPredicate used to compare items for "equality". This predicate can compute any relation between two items; it need not represent equality or an equivalence relation.

Returns

Type	Description
System.Boolean	True if predicatereturns true for each corresponding pair of items in the two collections. If both collections are empty, true is returned.

Type Parameters

Name	Description
T	The type of items in the collections.

Remarks

Since an arbitrary BinaryPredicate is passed to this function, what is being tested for need not be equality. For example, the following code determines if each integer in list1 is less than or equal to the corresponding integer in list2.

List<int> list1, list2;
if (EqualCollections(list1, list2, delegate(int x, int y) { return x <= y; }) {
    // the check is true...
}

Exceptions

Type	Condition
System.ArgumentNullException	collection1, collection2, or predicate is null.

EqualSets<T>(IEnumerable<T>, IEnumerable<T>)

Determines if two collections are equal, considered as sets. Two sets are equal if they have have the same items, with order not being significant.

Declaration

public static bool EqualSets<T>(IEnumerable<T> collection1, IEnumerable<T> collection2)

Parameters

Type	Name	Description
System.Collections.Generic.IEnumerable<T>	collection1	The first collection.
System.Collections.Generic.IEnumerable<T>	collection2	The second collection.

Returns

Type	Description
System.Boolean	True if collection1 are collection2 are equal, considered as sets.

Type Parameters

Name	Description
T

Remarks

The default sense of equality for T is used, as defined by T's implementation of IComparable<T>.Equals or object.Equals.

If both collections are Set, Bag, OrderedSet, or OrderedBag collections, it is more efficient to use the EqualTo method on that class.

Exceptions

Type	Condition
System.ArgumentNullException	collection1 or collection2 is null.

EqualSets<T>(IEnumerable<T>, IEnumerable<T>, IEqualityComparer<T>)

Determines if two collections are equal, considered as sets. Two sets are equal if they have have the same items, with order not being significant.

Declaration

public static bool EqualSets<T>(IEnumerable<T> collection1, IEnumerable<T> collection2, IEqualityComparer<T> equalityComparer)

Parameters

Type	Name	Description
System.Collections.Generic.IEnumerable<T>	collection1	The first collection.
System.Collections.Generic.IEnumerable<T>	collection2	The second collection.
System.Collections.Generic.IEqualityComparer<T>	equalityComparer	The IEqualityComparer<T> used to compare items for equality. Only the Equals and GetHashCode member functions of this interface are called.

Returns

Type	Description
System.Boolean	True if collection1 are collection2 are equal, considered as sets.

Type Parameters

Name	Description
T

Remarks

If both collections are Set, Bag, OrderedSet, or OrderedBag collections, it is more efficient to use the EqualTo method on that class.

Exceptions

Type	Condition
System.ArgumentNullException	collection1 or collection2 is null.

Exists<T>(IEnumerable<T>, Predicate<T>)

Determines if a collection contains any item that satisfies the condition defined by predicate.

Declaration

public static bool Exists<T>(IEnumerable<T> collection, Predicate<T> predicate)

Parameters

Type	Name	Description
System.Collections.Generic.IEnumerable<T>	collection	The collection to check all the items in.
System.Predicate<T>	predicate	A delegate that defines the condition to check for.

Returns

Type	Description
System.Boolean	True if the collection contains one or more items that satisfy the condition defined by predicate. False if the collection does not contain an item that satisfies predicate.

Type Parameters

Name	Description
T

Fill<T>(T[], T)

Replaces each item in a array with a given value.

Declaration

public static void Fill<T>(T[] array, T value)

Parameters

Type	Name	Description
T[]	array	The array to modify.
T	value	The value to fill with.

Type Parameters

Name	Description
T

Exceptions

Type	Condition
System.ArgumentNullException	array is null.

Fill<T>(IList<T>, T)

Replaces each item in a list with a given value. The list does not change in size.

Declaration

public static void Fill<T>(IList<T> list, T value)

Parameters

Type	Name	Description
System.Collections.Generic.IList<T>	list	The list to modify.
T	value	The value to fill with.

Type Parameters

Name	Description
T	The type of items in the list.

Exceptions

Type	Condition
System.ArgumentException	list is a read-only list.
System.ArgumentNullException	list is null.

FillRange<T>(T[], Int32, Int32, T)

Replaces each item in a part of a array with a given value.

Declaration

public static void FillRange<T>(T[] array, int start, int count, T value)

Parameters

Type	Name	Description
T[]	array	The array to modify.
System.Int32	start	The index at which to start filling. The first index in the array has index 0.
System.Int32	count	The number of items to fill.
T	value	The value to fill with.

Type Parameters

Name	Description
T

Exceptions

Type	Condition
System.ArgumentOutOfRangeException	start or count is negative, or start + count is greater than array.Length.
System.ArgumentNullException	array is null.

FillRange<T>(IList<T>, Int32, Int32, T)

Replaces each item in a part of a list with a given value.

Declaration

public static void FillRange<T>(IList<T> list, int start, int count, T value)

Parameters

Type	Name	Description
System.Collections.Generic.IList<T>	list	The list to modify.
System.Int32	start	The index at which to start filling. The first index in the list has index 0.
System.Int32	count	The number of items to fill.
T	value	The value to fill with.

Type Parameters

Name	Description
T	The type of items in the list.

Exceptions

Type	Condition
System.ArgumentException	list is a read-only list.
System.ArgumentOutOfRangeException	start or count is negative, or start + count is greater than list.Count.
System.ArgumentNullException	list is null.

FindFirstIndexWhere<T>(IList<T>, Predicate<T>)

Finds the index of the first item in a list that satisfies the condition defined by predicate.

Declaration

public static int FindFirstIndexWhere<T>(IList<T> list, Predicate<T> predicate)

Parameters

Type	Name	Description
System.Collections.Generic.IList<T>	list	The list to search.
System.Predicate<T>	predicate	A delegate that defined the condition to check for.

Returns

Type	Description
System.Int32	The index of the first item satisfying the condition. -1 if no such item exists in the list.

Type Parameters

Name	Description
T

FindFirstWhere<T>(IEnumerable<T>, Predicate<T>)

Finds the first item in a collection that satisfies the condition defined by predicate.

Declaration

public static T FindFirstWhere<T>(IEnumerable<T> collection, Predicate<T> predicate)

Parameters

Type	Name	Description
System.Collections.Generic.IEnumerable<T>	collection	The collection to search.
System.Predicate<T>	predicate	A delegate that defined the condition to check for.

Returns

Type	Description
T	The first item in the collection that matches the condition, or the default value for T (0 or null) if no item that matches the condition is found.

Type Parameters

Name	Description
T

Remarks

If the default value for T could be present in the collection, and would be matched by the predicate, then this method is inappropriate, because you cannot disguish whether the default value for T was actually present in the collection, or no items matched the predicate. In this case, use TryFindFirstWhere.

See Also

TryFindFirstWhere<T>(IEnumerable<T>, Predicate<T>, out T)

FindIndicesWhere<T>(IList<T>, Predicate<T>)

Enumerates the indices of all the items in list that satisfy the condition defined by predicate.

Declaration

public static IEnumerable<int> FindIndicesWhere<T>(IList<T> list, Predicate<T> predicate)

Parameters

Type	Name	Description
System.Collections.Generic.IList<T>	list	The list to check all the items in.
System.Predicate<T>	predicate	A delegate that defines the condition to check for.

Returns

Type	Description
System.Collections.Generic.IEnumerable<System.Int32>	An IEnumerable<T> that enumerates the indices of items that satisfy the condition.

Type Parameters

Name	Description
T

FindLastIndexWhere<T>(IList<T>, Predicate<T>)

Finds the index of the last item in a list that satisfies the condition defined by predicate.

Declaration

public static int FindLastIndexWhere<T>(IList<T> list, Predicate<T> predicate)

Parameters

Type	Name	Description
System.Collections.Generic.IList<T>	list	The list to search.
System.Predicate<T>	predicate	A delegate that defined the condition to check for.

Returns

Type	Description
System.Int32	The index of the last item satisfying the condition. -1 if no such item exists in the list.

Type Parameters

Name	Description
T

FindLastWhere<T>(IEnumerable<T>, Predicate<T>)

Finds the last item in a collection that satisfies the condition defined by predicate.

Declaration

public static T FindLastWhere<T>(IEnumerable<T> collection, Predicate<T> predicate)

Parameters

Type	Name	Description
System.Collections.Generic.IEnumerable<T>	collection	The collection to search.
System.Predicate<T>	predicate	A delegate that defined the condition to check for.

Returns

Type	Description
T	The last item in the collection that matches the condition, or the default value for T (0 or null) if no item that matches the condition is found.

Type Parameters

Name	Description
T

Remarks

If the collection implements IList<T>, then the list is scanned in reverse until a matching item is found. Otherwise, the entire collection is iterated in the forward direction.

If the default value for T could be present in the collection, and would be matched by the predicate, then this method is inappropriate, because you cannot disguish whether the default value for T was actually present in the collection, or no items matched the predicate. In this case, use TryFindFirstWhere.

See Also

TryFindLastWhere<T>(IEnumerable<T>, Predicate<T>, out T)

FindWhere<T>(IEnumerable<T>, Predicate<T>)

Enumerates all the items in collection that satisfy the condition defined by predicate.

Declaration

public static IEnumerable<T> FindWhere<T>(IEnumerable<T> collection, Predicate<T> predicate)

Parameters

Type	Name	Description
System.Collections.Generic.IEnumerable<T>	collection	The collection to check all the items in.
System.Predicate<T>	predicate	A delegate that defines the condition to check for.

Returns

Type	Description
System.Collections.Generic.IEnumerable<T>	An IEnumerable<T> that enumerates the items that satisfy the condition.

Type Parameters

Name	Description
T

FirstConsecutiveEqual<T>(IList<T>, Int32)

Finds the first occurence of count consecutive equal items in the list.

Declaration

public static int FirstConsecutiveEqual<T>(IList<T> list, int count)

Parameters

Type	Name	Description
System.Collections.Generic.IList<T>	list	The list to examine.
System.Int32	count	The number of consecutive equal items to look for. The count must be at least 1.

Returns

Type	Description
System.Int32	The index of the first item in the first run of count consecutive equal items, or -1 if no such run exists..

Type Parameters

Name	Description
T

Remarks

The default sense of equality for T is used, as defined by T's implementation of IComparable<T>.Equals or object.Equals.

FirstConsecutiveEqual<T>(IList<T>, Int32, IEqualityComparer<T>)

Finds the first occurence of count consecutive equal items in the list. A passed IEqualityComparer is used to determine equality.

Declaration

public static int FirstConsecutiveEqual<T>(IList<T> list, int count, IEqualityComparer<T> equalityComparer)

Parameters

Type	Name	Description
System.Collections.Generic.IList<T>	list	The list to examine.
System.Int32	count	The number of consecutive equal items to look for. The count must be at least 1.
System.Collections.Generic.IEqualityComparer<T>	equalityComparer	The IEqualityComparer<T> used to compare items for equality. Only the Equals method will be called.

Returns

Type	Description
System.Int32	The index of the first item in the first run of count consecutive equal items, or -1 if no such run exists.

Type Parameters

Name	Description
T

FirstConsecutiveEqual<T>(IList<T>, Int32, BinaryPredicate<T>)

Finds the first occurence of count consecutive "equal" items in the list. The passed BinaryPredicate is used to determine if two items are "equal".

Declaration

public static int FirstConsecutiveEqual<T>(IList<T> list, int count, BinaryPredicate<T> predicate)

Parameters

Type	Name	Description
System.Collections.Generic.IList<T>	list	The list to examine.
System.Int32	count	The number of consecutive equal items to look for. The count must be at least 1.
BinaryPredicate<T>	predicate	The BinaryPredicate used to compare items for "equality".

Returns

Type	Description
System.Int32	The index of the first item in the first run of count consecutive equal items, or -1 if no such run exists.

Type Parameters

Name	Description
T

Remarks

Since an arbitrary BinaryPredicate is passed to this function, what is being tested for need not be true equality.

FirstConsecutiveWhere<T>(IList<T>, Int32, Predicate<T>)

Finds the first occurence of count consecutive items in the list for which a given predicate returns true.

Declaration

public static int FirstConsecutiveWhere<T>(IList<T> list, int count, Predicate<T> predicate)

Parameters

Type	Name	Description
System.Collections.Generic.IList<T>	list	The list to examine.
System.Int32	count	The number of consecutive items to look for. The count must be at least 1.
System.Predicate<T>	predicate	The predicate used to test each item.

Returns

Type	Description
System.Int32	The index of the first item in the first run of count items where predicate returns true for all items in the run, or -1 if no such run exists.

Type Parameters

Name	Description
T

FirstIndexOf<T>(IList<T>, T)

Finds the index of the first item in a list equal to a given item.

Declaration

public static int FirstIndexOf<T>(IList<T> list, T item)

Parameters

Type	Name	Description
System.Collections.Generic.IList<T>	list	The list to search.
T	item	The item to search for.

Returns

Type	Description
System.Int32	The index of the first item equal to item. -1 if no such item exists in the list.

Type Parameters

Name	Description
T

Remarks

The default sense of equality for T is used, as defined by T's implementation of IComparable<T>.Equals or object.Equals.

FirstIndexOf<T>(IList<T>, T, IEqualityComparer<T>)

Finds the index of the first item in a list equal to a given item. A passed IEqualityComparer is used to determine equality.

Declaration

public static int FirstIndexOf<T>(IList<T> list, T item, IEqualityComparer<T> equalityComparer)

Parameters

Type	Name	Description
System.Collections.Generic.IList<T>	list	The list to search.
T	item	The item to search for.
System.Collections.Generic.IEqualityComparer<T>	equalityComparer	The IEqualityComparer<T> used to compare items for equality. Only the Equals method will be called.

Returns

Type	Description
System.Int32	The index of the first item equal to item. -1 if no such item exists in the list.

Type Parameters

Name	Description
T

FirstIndexOfMany<T>(IList<T>, IEnumerable<T>)

Finds the index of the first item in a list equal to one of several given items.

Declaration

public static int FirstIndexOfMany<T>(IList<T> list, IEnumerable<T> itemsToLookFor)

Parameters

Type	Name	Description
System.Collections.Generic.IList<T>	list	The list to search.
System.Collections.Generic.IEnumerable<T>	itemsToLookFor	The items to search for.

Returns

Type	Description
System.Int32	The index of the first item equal to any of the items in the collection itemsToLookFor. -1 if no such item exists in the list.

Type Parameters

Name	Description
T

Remarks

The default sense of equality for T is used, as defined by T's implementation of IComparable<T>.Equals or object.Equals.

FirstIndexOfMany<T>(IList<T>, IEnumerable<T>, IEqualityComparer<T>)

Finds the index of the first item in a list equal to one of several given items. A passed IEqualityComparer is used to determine equality.

Declaration

public static int FirstIndexOfMany<T>(IList<T> list, IEnumerable<T> itemsToLookFor, IEqualityComparer<T> equalityComparer)

Parameters

Type	Name	Description
System.Collections.Generic.IList<T>	list	The list to search.
System.Collections.Generic.IEnumerable<T>	itemsToLookFor	The items to search for.
System.Collections.Generic.IEqualityComparer<T>	equalityComparer	The IEqualityComparer<T> used to compare items for equality. Only the Equals and GetHashCode methods will be called.

Returns

Type	Description
System.Int32	The index of the first item equal to any of the items in the collection itemsToLookFor. -1 if no such item exists in the list.

Type Parameters

Name	Description
T

FirstIndexOfMany<T>(IList<T>, IEnumerable<T>, BinaryPredicate<T>)

Finds the index of the first item in a list "equal" to one of several given items. The passed BinaryPredicate is used to determine if two items are "equal".

Declaration

public static int FirstIndexOfMany<T>(IList<T> list, IEnumerable<T> itemsToLookFor, BinaryPredicate<T> predicate)

Parameters

Type	Name	Description
System.Collections.Generic.IList<T>	list	The list to search.
System.Collections.Generic.IEnumerable<T>	itemsToLookFor	The items to search for.
BinaryPredicate<T>	predicate	The BinaryPredicate used to compare items for "equality".

Returns

Type	Description
System.Int32	The index of the first item "equal" to any of the items in the collection itemsToLookFor, using BinaryPredicate as the test for equality. -1 if no such item exists in the list.

Type Parameters

Name	Description
T

Remarks

Since an arbitrary BinaryPredicate is passed to this function, what is being removed need not be true equality. This methods finds first item X which satisfies BinaryPredicate(X,Y), where Y is one of the items in itemsToLookFor

ForEach<T>(IEnumerable<T>, Action<T>)

Performs the specified action on each item in a collection.

Declaration

public static void ForEach<T>(IEnumerable<T> collection, Action<T> action)

Parameters

Type	Name	Description
System.Collections.Generic.IEnumerable<T>	collection	The collection to process.
System.Action<T>	action	An Action delegate which is invoked for each item in collection.

Type Parameters

Name	Description
T

GeneratePermutations<T>(IEnumerable<T>)

Generates all the possible permutations of the items in collection. If collection has N items, then N factorial permutations will be generated. This method does not compare the items to determine if any of them are equal. If some items are equal, the same permutation may be generated more than once. For example, if the collections contains the three items A, A, and B, then this method will generate the six permutations, AAB, AAB, ABA, ABA, BAA, BAA (not necessarily in that order). To take equal items into account, use the GenerateSortedPermutations method.

Declaration

public static IEnumerable<T[]> GeneratePermutations<T>(IEnumerable<T> collection)

Parameters

Type	Name	Description
System.Collections.Generic.IEnumerable<T>	collection	The collection of items to permute.

Returns

Type	Description
System.Collections.Generic.IEnumerable<T[]>	An IEnumerable<T[]> that enumerations all the possible permutations of the items in collection. Each permutations is returned as an array. The items in the array should be copied if they need to be used after the next permutation is generated; each permutation may reuse the same array instance.

Type Parameters

Name	Description
T	The type of items to permute.

GenerateSortedPermutations<T>(IEnumerable<T>)

Generates all the possible permutations of the items in collection, in lexicographical order. Even if some items are equal, the same permutation will not be generated more than once. For example, if the collections contains the three items A, A, and B, then this method will generate only the three permutations, AAB, ABA, BAA.

Declaration

public static IEnumerable<T[]> GenerateSortedPermutations<T>(IEnumerable<T> collection)
    where T : IComparable<T>

Parameters

Type	Name	Description
System.Collections.Generic.IEnumerable<T>	collection	The collection of items to permute.

Returns

Type	Description
System.Collections.Generic.IEnumerable<T[]>	An IEnumerable<T[]> that enumerations all the possible permutations of the items in collection. Each permutations is returned as an array. The items in the array should be copied if they need to be used after the next permutation is generated; each permutation may reuse the same array instance.

Type Parameters

Name	Description
T	The type of items to permute.

GenerateSortedPermutations<T>(IEnumerable<T>, IComparer<T>)

Generates all the possible permutations of the items in collection, in lexicographical order. A supplied IComparer<T> instance is used to compare the items. Even if some items are equal, the same permutation will not be generated more than once. For example, if the collections contains the three items A, A, and B, then this method will generate only the three permutations, AAB, ABA, BAA.

Declaration

public static IEnumerable<T[]> GenerateSortedPermutations<T>(IEnumerable<T> collection, IComparer<T> comparer)

Parameters

Type	Name	Description
System.Collections.Generic.IEnumerable<T>	collection	The collection of items to permute.
System.Collections.Generic.IComparer<T>	comparer	The IComparer<T> used to compare the items.

Returns

Type	Description
System.Collections.Generic.IEnumerable<T[]>	An IEnumerable<T[]> that enumerations all the possible permutations of the items in collection. Each permutations is returned as an array. The items in the array should be copied if they need to be used after the next permutation is generated; each permutation may reuse the same array instance.

Type Parameters

Name	Description
T	The type of items to permute.

GenerateSortedPermutations<T>(IEnumerable<T>, Comparison<T>)

Generates all the possible permutations of the items in collection, in lexicographical order. A supplied Comparison<T> delegate is used to compare the items. Even if some items are equal, the same permutation will not be generated more than once. For example, if the collections contains the three items A, A, and B, then this method will generate only the three permutations, AAB, ABA, BAA.

Declaration

public static IEnumerable<T[]> GenerateSortedPermutations<T>(IEnumerable<T> collection, Comparison<T> comparison)

Parameters

Type	Name	Description
System.Collections.Generic.IEnumerable<T>	collection	The collection of items to permute.
System.Comparison<T>	comparison	The Comparison<T> delegate used to compare the items.

Returns

Type	Description
System.Collections.Generic.IEnumerable<T[]>	An IEnumerable<T[]> that enumerations all the possible permutations of the items in collection. Each permutations is returned as an array. The items in the array should be copied if they need to be used after the next permutation is generated; each permutation may reuse the same array instance.

Type Parameters

Name	Description
T	The type of items to permute.

GetCollectionEqualityComparer<T>()

Gets an IEqualityComparer<IEnumerable<T>> implementation that can be used to compare collections of elements (of type T). Two collections of T's are equal if they have the same number of items, and corresponding items are equal, considered in order. This is the same notion of equality as in Algorithms.EqualCollections, but encapsulated in an IEqualityComparer<IEnumerable<T>> implementation.

Declaration

public static IEqualityComparer<IEnumerable<T>> GetCollectionEqualityComparer<T>()

Returns

Type	Description
System.Collections.Generic.IEqualityComparer<System.Collections.Generic.IEnumerable<T>>	IEqualityComparer<IEnumerable<T>> implementation suitable for comparing collections of T for equality.

Type Parameters

Name	Description
T

Examples

The following code creates a Dictionary where the keys are a collection of strings.

    Dictionary<IEnumerable<string>, int> = 
        new Dictionary<IEnumerable<string>, int>(Algorithms.GetCollectionEqualityComparer<string>());

See Also

EqualCollections<T>(IEnumerable<T>, IEnumerable<T>)

GetCollectionEqualityComparer<T>(IEqualityComparer<T>)

Gets an IEqualityComparer<IEnumerable<T>> implementation that can be used to compare collections of elements (of type T). Two collections of T's are equal if they have the same number of items, and corresponding items are equal, considered in order. This is the same notion of equality as in Algorithms.EqualCollections, but encapsulated in an IEqualityComparer<IEnumerable<T>> implementation.

An IEqualityComparer<T> is used to determine if individual T's are equal

Declaration

public static IEqualityComparer<IEnumerable<T>> GetCollectionEqualityComparer<T>(IEqualityComparer<T> equalityComparer)

Parameters

Type	Name	Description
System.Collections.Generic.IEqualityComparer<T>	equalityComparer	An IEqualityComparer<T> implementation used to compare individual T's.

Returns

Type	Description
System.Collections.Generic.IEqualityComparer<System.Collections.Generic.IEnumerable<T>>	IEqualityComparer<IEnumerable<T>> implementation suitable for comparing collections of T for equality.

Type Parameters

Name	Description
T

Examples

The following code creates a Dictionary where the keys are a collection of strings, compared in a case-insensitive way

    Dictionary<IEnumerable<string>, int> = 
        new Dictionary<IEnumerable<string>, int>(Algorithms.GetCollectionEqualityComparer<string>(StringComparer.CurrentCultureIgnoreCase));

See Also

EqualCollections<T>(IEnumerable<T>, IEnumerable<T>)

GetComparerFromComparison<T>(Comparison<T>)

Given a comparison delegate that compares two items of type T, gets an IComparer<T> instance that performs the same comparison.

Declaration

public static IComparer<T> GetComparerFromComparison<T>(Comparison<T> comparison)

Parameters

Type	Name	Description
System.Comparison<T>	comparison	The comparison delegate to use.

Returns

Type	Description
System.Collections.Generic.IComparer<T>	An IComparer<T> that performs the same comparing operation as comparison.

Type Parameters

Name	Description
T

GetComparisonFromComparer<T>(IComparer<T>)

Given in IComparer<T> instenace that comparers two items from type T, gets a Comparison delegate that performs the same comparison.

Declaration

public static Comparison<T> GetComparisonFromComparer<T>(IComparer<T> comparer)

Parameters

Type	Name	Description
System.Collections.Generic.IComparer<T>	comparer	The IComparer<T> instance to use.

Returns

Type	Description
System.Comparison<T>	A Comparison<T> delegate that performans the same comparing operation as comparer.

Type Parameters

Name	Description
T

GetDictionaryConverter<TKey, TValue>(IDictionary<TKey, TValue>)

Creates a delegate that converts keys to values by used a dictionary to map values. Keys that a not present in the dictionary are converted to the default value (zero or null).

Declaration

public static Converter<TKey, TValue> GetDictionaryConverter<TKey, TValue>(IDictionary<TKey, TValue> dictionary)

Parameters

Type	Name	Description
System.Collections.Generic.IDictionary<TKey, TValue>	dictionary	The dictionary used to perform the conversion.

Returns

Type	Description
System.Converter<TKey, TValue>	A delegate to a method that converts keys to values.

Type Parameters

Name	Description
TKey
TValue

Remarks

This delegate can be used as a parameter in Convert or ConvertAll methods to convert entire collections.

GetDictionaryConverter<TKey, TValue>(IDictionary<TKey, TValue>, TValue)

Creates a delegate that converts keys to values by used a dictionary to map values. Keys that a not present in the dictionary are converted to a supplied default value.

Declaration

public static Converter<TKey, TValue> GetDictionaryConverter<TKey, TValue>(IDictionary<TKey, TValue> dictionary, TValue defaultValue)

Parameters

Type	Name	Description
System.Collections.Generic.IDictionary<TKey, TValue>	dictionary	The dictionary used to perform the conversion.
TValue	defaultValue	The result of the conversion for keys that are not present in the dictionary.

Returns

Type	Description
System.Converter<TKey, TValue>	A delegate to a method that converts keys to values.

Type Parameters

Name	Description
TKey
TValue

Remarks

This delegate can be used as a parameter in Convert or ConvertAll methods to convert entire collections.

Exceptions

Type	Condition
System.ArgumentNullException	dictionary is null.

GetIdentityComparer<T>()

Gets an IEqualityComparer<T> instance that can be used to compare objects of type T for object identity only. Two objects compare equal only if they are references to the same object.

Declaration

public static IEqualityComparer<T> GetIdentityComparer<T>()
    where T : class

Returns

Type	Description
System.Collections.Generic.IEqualityComparer<T>	An IEqualityComparer<T> instance for identity comparison.

Type Parameters

Name	Description
T

GetLexicographicalComparer<T>()

Creates an IComparer instance that can be used for comparing ordered sequences of type T; that is IEnumerable<Tgt;. This comparer can be used for collections or algorithms that use sequences of T as an item type. The Lexicographical ordered of sequences is for comparison.

Declaration

public static IComparer<IEnumerable<T>> GetLexicographicalComparer<T>()
    where T : IComparable<T>

Returns

Type	Description
System.Collections.Generic.IComparer<System.Collections.Generic.IEnumerable<T>>	At IComparer<IEnumerable<T>> that compares sequences of T.

Type Parameters

Name	Description
T

Remarks

T must implement either IComparable<T> and this implementation is used to compare the items.

GetLexicographicalComparer<T>(IComparer<T>)

Creates an IComparer instance that can be used for comparing ordered sequences of type T; that is IEnumerable<Tgt;. This comparer can be uses for collections or algorithms that use sequences of T as an item type. The Lexicographics ordered of sequences is for comparison.

Declaration

public static IComparer<IEnumerable<T>> GetLexicographicalComparer<T>(IComparer<T> comparer)

Parameters

Type	Name	Description
System.Collections.Generic.IComparer<T>	comparer	A comparer instance used to compare individual items of type T.

Returns

Type	Description
System.Collections.Generic.IComparer<System.Collections.Generic.IEnumerable<T>>	At IComparer<IEnumerable<T>> that compares sequences of T.

Type Parameters

Name	Description
T

GetLexicographicalComparer<T>(Comparison<T>)

Creates an IComparer instance that can be used for comparing ordered sequences of type T; that is IEnumerable<Tgt;. This comparer can be uses for collections or algorithms that use sequences of T as an item type. The Lexicographics ordered of sequences is for comparison.

Declaration

public static IComparer<IEnumerable<T>> GetLexicographicalComparer<T>(Comparison<T> comparison)

Parameters

Type	Name	Description
System.Comparison<T>	comparison	A comparison delegate used to compare individual items of type T.

Returns

Type	Description
System.Collections.Generic.IComparer<System.Collections.Generic.IEnumerable<T>>	At IComparer<IEnumerable<T>> that compares sequences of T.

Type Parameters

Name	Description
T

GetReverseComparer<T>(IComparer<T>)

Reverses the order of comparison of an IComparer<T>. The resulting comparer can be used, for example, to sort a collection in descending order. Equality and hash codes are unchanged.

Declaration

public static IComparer<T> GetReverseComparer<T>(IComparer<T> comparer)

Parameters

Type	Name	Description
System.Collections.Generic.IComparer<T>	comparer	The comparer to reverse.

Returns

Type	Description
System.Collections.Generic.IComparer<T>	An IComparer<T> that compares items in the reverse order of comparer.

Type Parameters

Name	Description
T	The type of items thta are being compared.

Exceptions

Type	Condition
System.ArgumentNullException	comparer is null.

GetReverseComparison<T>(Comparison<T>)

Reverses the order of comparison of an Comparison<T>. The resulting comparison can be used, for example, to sort a collection in descending order.

Declaration

public static Comparison<T> GetReverseComparison<T>(Comparison<T> comparison)

Parameters

Type	Name	Description
System.Comparison<T>	comparison	The comparison to reverse.

Returns

Type	Description
System.Comparison<T>	A Comparison<T> that compares items in the reverse order of comparison.

Type Parameters

Name	Description
T	The type of items that are being compared.

Exceptions

Type	Condition
System.ArgumentNullException	comparison is null.

GetSetEqualityComparer<T>()

Gets an IEqualityComparer<IEnumerable<T>> implementation that can be used to compare collections of elements (of type T). Two collections of T's are equal if they have the same number of items, and corresponding items are equal, without regard to order. This is the same notion of equality as in Algorithms.EqualSets, but encapsulated in an IEqualityComparer<IEnumerable<T>> implementation.

An IEqualityComparer<T> is used to determine if individual T's are equal

Declaration

public static IEqualityComparer<IEnumerable<T>> GetSetEqualityComparer<T>()

Returns

Type	Description
System.Collections.Generic.IEqualityComparer<System.Collections.Generic.IEnumerable<T>>	IEqualityComparer<IEnumerable<T>> implementation suitable for comparing collections of T for equality, without regard to order.

Type Parameters

Name	Description
T

Examples

The following code creates a Dictionary where the keys are a set of strings, without regard to order

    Dictionary<IEnumerable<string>, int> = 
        new Dictionary<IEnumerable<string>, int>(Algorithms.GetSetEqualityComparer<string>(StringComparer.CurrentCultureIgnoreCase));

See Also

EqualSets<T>(IEnumerable<T>, IEnumerable<T>)

GetSetEqualityComparer<T>(IEqualityComparer<T>)

Gets an IEqualityComparer<IEnumerable<T>> implementation that can be used to compare collections of elements (of type T). Two collections of T's are equal if they have the same number of items, and corresponding items are equal, without regard to order. This is the same notion of equality as in Algorithms.EqualSets, but encapsulated in an IEqualityComparer<IEnumerable<T>> implementation.

Declaration

public static IEqualityComparer<IEnumerable<T>> GetSetEqualityComparer<T>(IEqualityComparer<T> equalityComparer)

Parameters

Type	Name	Description
System.Collections.Generic.IEqualityComparer<T>	equalityComparer	An IEqualityComparer<T> implementation used to compare individual T's.

Returns

Type	Description
System.Collections.Generic.IEqualityComparer<System.Collections.Generic.IEnumerable<T>>	IEqualityComparer<IEnumerable<T>> implementation suitable for comparing collections of T for equality, without regard to order.

Type Parameters

Name	Description
T

Examples

The following code creates a Dictionary where the keys are a set of strings, without regard to order

    Dictionary<IEnumerable<string>, int> = 
        new Dictionary<IEnumerable<string>, int>(Algorithms.GetSetEqualityComparer<string>());

See Also

EqualSets<T>(IEnumerable<T>, IEnumerable<T>)

IndexOfMaximum<T>(IList<T>)

Finds the index of the maximum value in a list.

Declaration

public static int IndexOfMaximum<T>(IList<T> list)
    where T : IComparable<T>

Parameters

Type	Name	Description
System.Collections.Generic.IList<T>	list	The list to search.

Returns

Type	Description
System.Int32	The index of the largest item in the list. If the maximum value appears multiple times, the index of the first appearance is used. If the list is empty, -1 is returned.

Type Parameters

Name	Description
T	The type of items in the list.

Remarks

Values in the list are compared by using the IComparable<T> interfaces implementation on the type T.

Exceptions

Type	Condition
System.ArgumentNullException	list is null.

IndexOfMaximum<T>(IList<T>, IComparer<T>)

Finds the index of the maximum value in a list. A supplied IComparer<T> is used to compare the items in the collection.

Declaration

public static int IndexOfMaximum<T>(IList<T> list, IComparer<T> comparer)

Parameters

Type	Name	Description
System.Collections.Generic.IList<T>	list	The list to search.
System.Collections.Generic.IComparer<T>	comparer	The comparer instance used to compare items in the collection.

Returns

Type	Description
System.Int32	The index of the largest item in the list. If the maximum value appears multiple times, the index of the first appearance is used. If the list is empty, -1 is returned.

Type Parameters

Name	Description
T	The type of items in the list.

Exceptions

Type	Condition
System.ArgumentNullException	list or comparer is null.

IndexOfMaximum<T>(IList<T>, Comparison<T>)

Finds the index of the maximum value in a list. A supplied Comparison<T> delegate is used to compare the items in the collection.

Declaration

public static int IndexOfMaximum<T>(IList<T> list, Comparison<T> comparison)

Parameters

Type	Name	Description
System.Collections.Generic.IList<T>	list	The list to search.
System.Comparison<T>	comparison	The comparison used to compare items in the collection.

Returns

Type	Description
System.Int32	The index of the largest item in the list. If the maximum value appears multiple times, the index of the first appearance is used. If the list is empty, -1 is returned.

Type Parameters

Name	Description
T	The type of items in the list.

Exceptions

Type	Condition
System.ArgumentNullException	list or comparison is null.

IndexOfMinimum<T>(IList<T>)

Finds the index of the minimum value in a list.

Declaration

public static int IndexOfMinimum<T>(IList<T> list)
    where T : IComparable<T>

Parameters

Type	Name	Description
System.Collections.Generic.IList<T>	list	The list to search.

Returns

Type	Description
System.Int32	The index of the smallest item in the list. If the minimum value appears multiple times, the index of the first appearance is used.

Type Parameters

Name	Description
T	The type of items in the list.

Remarks

Values in the list are compared by using the IComparable<T> interfaces implementation on the type T.

Exceptions

Type	Condition
System.InvalidOperationException	The collection is empty.
System.ArgumentNullException	list is null.

IndexOfMinimum<T>(IList<T>, IComparer<T>)

Finds the index of the minimum value in a list. A supplied IComparer<T> is used to compare the items in the collection.

Declaration

public static int IndexOfMinimum<T>(IList<T> list, IComparer<T> comparer)

Parameters

Type	Name	Description
System.Collections.Generic.IList<T>	list	The list to search.
System.Collections.Generic.IComparer<T>	comparer	The comparer instance used to compare items in the collection.

Returns

Type	Description
System.Int32	The index of the smallest item in the list. If the minimum value appears multiple times, the index of the first appearance is used.

Type Parameters

Name	Description
T	The type of items in the list.

Exceptions

Type	Condition
System.InvalidOperationException	The collection is empty.
System.ArgumentNullException	list or comparer is null.

IndexOfMinimum<T>(IList<T>, Comparison<T>)

Finds the index of the minimum value in a list. A supplied Comparison<T> delegate is used to compare the items in the collection.

Declaration

public static int IndexOfMinimum<T>(IList<T> list, Comparison<T> comparison)

Parameters

Type	Name	Description
System.Collections.Generic.IList<T>	list	The list to search.
System.Comparison<T>	comparison	The comparison delegate used to compare items in the collection.

Returns

Type	Description
System.Int32	The index of the smallest item in the list. If the minimum value appears multiple times, the index of the first appearance is used.

Type Parameters

Name	Description
T	The type of items in the list.

Exceptions

Type	Condition
System.InvalidOperationException	The collection is empty.
System.ArgumentNullException	list or comparison is null.

IndicesOf<T>(IList<T>, T)

Enumerates the indices of all the items in a list equal to a given item.

Declaration

public static IEnumerable<int> IndicesOf<T>(IList<T> list, T item)

Parameters

Type	Name	Description
System.Collections.Generic.IList<T>	list	The list to search.
T	item	The item to search for.

Returns

Type	Description
System.Collections.Generic.IEnumerable<System.Int32>	An IEnumerable<T> that enumerates the indices of items equal to item.

Type Parameters

Name	Description
T

Remarks

The default sense of equality for T is used, as defined by T's implementation of IComparable<T>.Equals or object.Equals.

IndicesOf<T>(IList<T>, T, IEqualityComparer<T>)

Enumerates the indices of all the items in a list equal to a given item. A passed IEqualityComparer is used to determine equality.

Declaration

public static IEnumerable<int> IndicesOf<T>(IList<T> list, T item, IEqualityComparer<T> equalityComparer)

Parameters

Type	Name	Description
System.Collections.Generic.IList<T>	list	The list to search.
T	item	The item to search for.
System.Collections.Generic.IEqualityComparer<T>	equalityComparer	The IEqualityComparer<T> used to compare items for equality. Only the Equals method will be called.

Returns

Type	Description
System.Collections.Generic.IEnumerable<System.Int32>	An IEnumerable<T> that enumerates the indices of items equal to item.

Type Parameters

Name	Description
T

IndicesOfMany<T>(IList<T>, IEnumerable<T>)

Enumerates the indices of all the items in a list equal to one of several given items.

Declaration

public static IEnumerable<int> IndicesOfMany<T>(IList<T> list, IEnumerable<T> itemsToLookFor)

Parameters

Type	Name	Description
System.Collections.Generic.IList<T>	list	The list to search.
System.Collections.Generic.IEnumerable<T>	itemsToLookFor	A collection of items to search for.

Returns

Type	Description
System.Collections.Generic.IEnumerable<System.Int32>	An IEnumerable<T> that enumerates the indices of items equal to any of the items in the collection itemsToLookFor.

Type Parameters

Name	Description
T

Remarks

The default sense of equality for T is used, as defined by T's implementation of IComparable<T>.Equals or object.Equals.

IndicesOfMany<T>(IList<T>, IEnumerable<T>, IEqualityComparer<T>)

Enumerates the indices of all the items in a list equal to one of several given items. A passed IEqualityComparer is used to determine equality.

Declaration

public static IEnumerable<int> IndicesOfMany<T>(IList<T> list, IEnumerable<T> itemsToLookFor, IEqualityComparer<T> equalityComparer)

Parameters

Type	Name	Description
System.Collections.Generic.IList<T>	list	The list to search.
System.Collections.Generic.IEnumerable<T>	itemsToLookFor	A collection of items to search for.
System.Collections.Generic.IEqualityComparer<T>	equalityComparer	The IEqualityComparer<T> used to compare items for equality.

Returns

Type	Description
System.Collections.Generic.IEnumerable<System.Int32>	An IEnumerable<T> that enumerates the indices of items equal to any of the items in the collection itemsToLookFor.

Type Parameters

Name	Description
T

IndicesOfMany<T>(IList<T>, IEnumerable<T>, BinaryPredicate<T>)

Enumerates the indices of all the items in a list equal to one of several given items. The passed BinaryPredicate is used to determine if two items are "equal".

Declaration

public static IEnumerable<int> IndicesOfMany<T>(IList<T> list, IEnumerable<T> itemsToLookFor, BinaryPredicate<T> predicate)

Parameters

Type	Name	Description
System.Collections.Generic.IList<T>	list	The list to search.
System.Collections.Generic.IEnumerable<T>	itemsToLookFor	A collection of items to search for.
BinaryPredicate<T>	predicate	The BinaryPredicate used to compare items for "equality".

Returns

Type	Description
System.Collections.Generic.IEnumerable<System.Int32>	An IEnumerable<T> that enumerates the indices of items "equal" to any of the items in the collection itemsToLookFor, using BinaryPredicate as the test for equality.

Type Parameters

Name	Description
T

Remarks

Since an arbitrary BinaryPredicate is passed to this function, what is being removed need not be true equality. This methods finds last item X which satisfies BinaryPredicate(X,Y), where Y is one of the items in itemsToLookFor

IsProperSubsetOf<T>(IEnumerable<T>, IEnumerable<T>)

Determines if one collection is a proper subset of another, considered as sets. The first set is a proper subset of the second set if every item in the first set also occurs in the second set, and the first set is strictly smaller than the second set. If an item appears X times in the first set, it must appear at least X times in the second set.

Declaration

public static bool IsProperSubsetOf<T>(IEnumerable<T> collection1, IEnumerable<T> collection2)

Parameters

Type	Name	Description
System.Collections.Generic.IEnumerable<T>	collection1	The first collection.
System.Collections.Generic.IEnumerable<T>	collection2	The second collection.

Returns

Type	Description
System.Boolean	True if collection1 is a subset of collection2, considered as sets.

Type Parameters

Name	Description
T

Remarks

The default sense of equality for T is used, as defined by T's implementation of IComparable<T>.Equals or object.Equals.

If both collections are Set, Bag, OrderedSet, or OrderedBag collections, it is more efficient to use the IsSubsetOf method on that class.

Exceptions

Type	Condition
System.ArgumentNullException	collection1 or collection2 is null.

IsProperSubsetOf<T>(IEnumerable<T>, IEnumerable<T>, IEqualityComparer<T>)

Determines if one collection is a proper subset of another, considered as sets. The first set is a proper subset of the second set if every item in the first set also occurs in the second set, and the first set is strictly smaller than the second set. If an item appears X times in the first set, it must appear at least X times in the second set.

Declaration

public static bool IsProperSubsetOf<T>(IEnumerable<T> collection1, IEnumerable<T> collection2, IEqualityComparer<T> equalityComparer)

Parameters

Type	Name	Description
System.Collections.Generic.IEnumerable<T>	collection1	The first collection.
System.Collections.Generic.IEnumerable<T>	collection2	The second collection.
System.Collections.Generic.IEqualityComparer<T>	equalityComparer	The IEqualityComparer<T> used to compare items for equality. Only the Equals and GetHashCode member functions of this interface are called.

Returns

Type	Description
System.Boolean	True if collection1 is a proper subset of collection2, considered as sets.

Type Parameters

Name	Description
T

Remarks

If both collections are Set, Bag, OrderedSet, or OrderedBag collections, it is more efficient to use the IsSubsetOf method on that class.

Exceptions

Type	Condition
System.ArgumentNullException	collection1 or collection2 is null.

IsSubsetOf<T>(IEnumerable<T>, IEnumerable<T>)

Determines if one collection is a subset of another, considered as sets. The first set is a subset of the second set if every item in the first set also occurs in the second set. If an item appears X times in the first set, it must appear at least X times in the second set.

Declaration

public static bool IsSubsetOf<T>(IEnumerable<T> collection1, IEnumerable<T> collection2)

Parameters

Type	Name	Description
System.Collections.Generic.IEnumerable<T>	collection1	The first collection.
System.Collections.Generic.IEnumerable<T>	collection2	The second collection.

Returns

Type	Description
System.Boolean	True if collection1 is a subset of collection2, considered as sets.

Type Parameters

Name	Description
T

Remarks

The default sense of equality for T is used, as defined by T's implementation of IComparable<T>.Equals or object.Equals.

If both collections are Set, Bag, OrderedSet, or OrderedBag collections, it is more efficient to use the IsSubsetOf method on that class.

Exceptions

Type	Condition
System.ArgumentNullException	collection1 or collection2 is null.

IsSubsetOf<T>(IEnumerable<T>, IEnumerable<T>, IEqualityComparer<T>)

Determines if one collection is a subset of another, considered as sets. The first set is a subset of the second set if every item in the first set also occurs in the second set. If an item appears X times in the first set, it must appear at least X times in the second set.

Declaration

public static bool IsSubsetOf<T>(IEnumerable<T> collection1, IEnumerable<T> collection2, IEqualityComparer<T> equalityComparer)

Parameters

Type	Name	Description
System.Collections.Generic.IEnumerable<T>	collection1	The first collection.
System.Collections.Generic.IEnumerable<T>	collection2	The second collection.
System.Collections.Generic.IEqualityComparer<T>	equalityComparer	The IEqualityComparer<T> used to compare items for equality.

Returns

Type	Description
System.Boolean	True if collection1 is a subset of collection2, considered as sets.

Type Parameters

Name	Description
T

Remarks

If both collections are Set, Bag, OrderedSet, or OrderedBag collections, it is more efficient to use the IsSubsetOf method on that class.

Exceptions

Type	Condition
System.ArgumentNullException	collection1 or collection2 is null.

LastIndexOf<T>(IList<T>, T)

Finds the index of the last item in a list equal to a given item.

Declaration

public static int LastIndexOf<T>(IList<T> list, T item)

Parameters

Type	Name	Description
System.Collections.Generic.IList<T>	list	The list to search.
T	item	The item to search for.

Returns

Type	Description
System.Int32	The index of the last item equal to item. -1 if no such item exists in the list.

Type Parameters

Name	Description
T

Remarks

The default sense of equality for T is used, as defined by T's implementation of IComparable<T>.Equals or object.Equals.

LastIndexOf<T>(IList<T>, T, IEqualityComparer<T>)

Finds the index of the last item in a list equal to a given item. A passed IEqualityComparer is used to determine equality.

Declaration

public static int LastIndexOf<T>(IList<T> list, T item, IEqualityComparer<T> equalityComparer)

Parameters

Type	Name	Description
System.Collections.Generic.IList<T>	list	The list to search.
T	item	The item to search for.
System.Collections.Generic.IEqualityComparer<T>	equalityComparer	The IEqualityComparer<T> used to compare items for equality. Only the Equals method will be called.

Returns

Type	Description
System.Int32	The index of the last item equal to item. -1 if no such item exists in the list.

Type Parameters

Name	Description
T

LastIndexOfMany<T>(IList<T>, IEnumerable<T>)

Finds the index of the last item in a list equal to one of several given items.

Declaration

public static int LastIndexOfMany<T>(IList<T> list, IEnumerable<T> itemsToLookFor)

Parameters

Type	Name	Description
System.Collections.Generic.IList<T>	list	The list to search.
System.Collections.Generic.IEnumerable<T>	itemsToLookFor	The items to search for.

Returns

Type	Description
System.Int32	The index of the last item equal to any of the items in the collection itemsToLookFor. -1 if no such item exists in the list.

Type Parameters

Name	Description
T

Remarks

The default sense of equality for T is used, as defined by T's implementation of IComparable<T>.Equals or object.Equals.

LastIndexOfMany<T>(IList<T>, IEnumerable<T>, IEqualityComparer<T>)

Finds the index of the last item in a list equal to one of several given items. A passed IEqualityComparer is used to determine equality.

Declaration

public static int LastIndexOfMany<T>(IList<T> list, IEnumerable<T> itemsToLookFor, IEqualityComparer<T> equalityComparer)

Parameters

Type	Name	Description
System.Collections.Generic.IList<T>	list	The list to search.
System.Collections.Generic.IEnumerable<T>	itemsToLookFor	The items to search for.
System.Collections.Generic.IEqualityComparer<T>	equalityComparer	The IEqualityComparer<T> used to compare items for equality.

Returns

Type	Description
System.Int32	The index of the last item equal to any of the items in the collection itemsToLookFor. -1 if no such item exists in the list.

Type Parameters

Name	Description
T

LastIndexOfMany<T>(IList<T>, IEnumerable<T>, BinaryPredicate<T>)

Finds the index of the last item in a list "equal" to one of several given items. The passed BinaryPredicate is used to determine if two items are "equal".

Declaration

public static int LastIndexOfMany<T>(IList<T> list, IEnumerable<T> itemsToLookFor, BinaryPredicate<T> predicate)

Parameters

Type	Name	Description
System.Collections.Generic.IList<T>	list	The list to search.
System.Collections.Generic.IEnumerable<T>	itemsToLookFor	The items to search for.
BinaryPredicate<T>	predicate	The BinaryPredicate used to compare items for "equality".

Returns

Type	Description
System.Int32	The index of the last item "equal" to any of the items in the collection itemsToLookFor, using BinaryPredicate as the test for equality. -1 if no such item exists in the list.

Type Parameters

Name	Description
T

Remarks

Since an arbitrary BinaryPredicate is passed to this function, what is being removed need not be true equality. This methods finds last item X which satisfies BinaryPredicate(X,Y), where Y is one of the items in itemsToLookFor

LexicographicalCompare<T>(IEnumerable<T>, IEnumerable<T>)

Performs a lexicographical comparison of two sequences of values. A lexicographical comparison compares corresponding pairs of elements from two sequences in order. If the first element of sequence1 is less than the first element of sequence2, then the comparison ends and the first sequence is lexicographically less than the second. If the first elements of each sequence are equal, then the comparison proceeds to the second element of each sequence. If one sequence is shorter than the other, but corresponding elements are all equal, then the shorter sequence is considered less than the longer one.

Declaration

public static int LexicographicalCompare<T>(IEnumerable<T> sequence1, IEnumerable<T> sequence2)
    where T : IComparable<T>

Parameters

Type	Name	Description
System.Collections.Generic.IEnumerable<T>	sequence1	The first sequence to compare.
System.Collections.Generic.IEnumerable<T>	sequence2	The second sequence to compare.

Returns

Type	Description
System.Int32	Less than zero if sequence1 is lexicographically less than sequence2. Greater than zero if sequence1 is lexicographically greater than sequence2. Zero if sequence1 is equal to sequence2.

Type Parameters

Name	Description
T	Types of items to compare. This type must implement IComparable<T> to allow items to be compared.

Remarks

T must implement either IComparable<T> and this implementation is used to compare the items.

Exceptions

Type	Condition
System.NotSupportedException	T does not implement IComparable<T> or IComparable.

LexicographicalCompare<T>(IEnumerable<T>, IEnumerable<T>, IComparer<T>)

Performs a lexicographical comparison of two sequences of values, using a supplied comparer interface. A lexicographical comparison compares corresponding pairs of elements from two sequences in order. If the first element of sequence1 is less than the first element of sequence2, then the comparison ends and the first sequence is lexicographically less than the second. If the first elements of each sequence are equal, then the comparison proceeds to the second element of each sequence. If one sequence is shorter than the other, but corresponding elements are all equal, then the shorter sequence is considered less than the longer one.

Declaration

public static int LexicographicalCompare<T>(IEnumerable<T> sequence1, IEnumerable<T> sequence2, IComparer<T> comparer)

Parameters

Type	Name	Description
System.Collections.Generic.IEnumerable<T>	sequence1	The first sequence to compare.
System.Collections.Generic.IEnumerable<T>	sequence2	The second sequence to compare.
System.Collections.Generic.IComparer<T>	comparer	The IComparer<T> used to compare items. Only the Compare member function of this interface is called.

Returns

Type	Description
System.Int32	Less than zero if sequence1 is lexicographically less than sequence2. Greater than zero if sequence1 is lexicographically greater than sequence2. Zero if sequence1 is equal to sequence2.

Type Parameters

Name	Description
T	Types of items to compare.

Exceptions

Type	Condition
System.ArgumentNullException	sequence1, sequence2, or comparer is null.

LexicographicalCompare<T>(IEnumerable<T>, IEnumerable<T>, Comparison<T>)

Performs a lexicographical comparison of two sequences of values, using a supplied comparison delegate. A lexicographical comparison compares corresponding pairs of elements from two sequences in order. If the first element of sequence1 is less than the first element of sequence2, then the comparison ends and the first sequence is lexicographically less than the second. If the first elements of each sequence are equal, then the comparison proceeds to the second element of each sequence. If one sequence is shorter than the other, but corresponding elements are all equal, then the shorter sequence is considered less than the longer one.

Declaration

public static int LexicographicalCompare<T>(IEnumerable<T> sequence1, IEnumerable<T> sequence2, Comparison<T> comparison)

Parameters

Type	Name	Description
System.Collections.Generic.IEnumerable<T>	sequence1	The first sequence to compare.
System.Collections.Generic.IEnumerable<T>	sequence2	The second sequence to compare.
System.Comparison<T>	comparison	The IComparison<T> delegate to compare items. Only the Compare member function of this interface is called.

Returns

Type	Description
System.Int32	Less than zero if sequence1 is lexicographically less than sequence2. Greater than zero if sequence1 is lexicographically greater than sequence2. Zero if sequence1 is equal to sequence2.

Type Parameters

Name	Description
T	Types of items to compare.

Maximum<T>(IEnumerable<T>)

Finds the maximum value in a collection.

Declaration

public static T Maximum<T>(IEnumerable<T> collection)
    where T : IComparable<T>

Parameters

Type	Name	Description
System.Collections.Generic.IEnumerable<T>	collection	The collection to search.

Returns

Type	Description
T	The largest item in the collection.

Type Parameters

Name	Description
T	The type of items in the collection.

Remarks

Values in the collection are compared by using the IComparable<T> interfaces implementation on the type T.

Exceptions

Type	Condition
System.InvalidOperationException	The collection is empty.
System.ArgumentNullException	collection is null.

Maximum<T>(IEnumerable<T>, IComparer<T>)

Finds the maximum value in a collection. A supplied IComparer<T> is used to compare the items in the collection.

Declaration

public static T Maximum<T>(IEnumerable<T> collection, IComparer<T> comparer)

Parameters

Type	Name	Description
System.Collections.Generic.IEnumerable<T>	collection	The collection to search.
System.Collections.Generic.IComparer<T>	comparer	The comparer instance used to compare items in the collection.

Returns

Type	Description
T	The largest item in the collection.

Type Parameters

Name	Description
T	The type of items in the collection.

Exceptions

Type	Condition
System.InvalidOperationException	The collection is empty.
System.ArgumentNullException	collection or comparer is null.

Maximum<T>(IEnumerable<T>, Comparison<T>)

Finds the maximum value in a collection. A supplied Comparison<T> delegate is used to compare the items in the collection.

Declaration

public static T Maximum<T>(IEnumerable<T> collection, Comparison<T> comparison)

Parameters

Type	Name	Description
System.Collections.Generic.IEnumerable<T>	collection	The collection to search.
System.Comparison<T>	comparison	The comparison used to compare items in the collection.

Returns

Type	Description
T	The largest item in the collection.

Type Parameters

Name	Description
T	The type of items in the collection.

Exceptions

Type	Condition
System.InvalidOperationException	The collection is empty.
System.ArgumentNullException	collection or comparison is null.

MergeSorted<T>(IComparer<T>, IEnumerable<T>[])

Merge several sorted collections into a single sorted collection. Each input collection must be sorted by the ordering in the passed instance of IComparer<T>. The merging is stable; equal items maintain their ordering, and equal items in different collections are placed in the order of the collections.

Declaration

public static IEnumerable<T> MergeSorted<T>(IComparer<T> comparer, params IEnumerable<T>[] collections)

Parameters

Type	Name	Description
System.Collections.Generic.IComparer<T>	comparer	The comparer instance used to sort the list. Only the Compare method is used.
System.Collections.Generic.IEnumerable<T>[]	collections	The set of collections to merge. In many languages, this parameter can be specified as several individual parameters.

Returns

Type	Description
System.Collections.Generic.IEnumerable<T>	An IEnumerable<T> that enumerates all the items in all the collections in sorted order.

Type Parameters

Name	Description
T

MergeSorted<T>(IEnumerable<T>[])

Merge several sorted collections into a single sorted collection. Each input collection must be sorted by the natural ordering of the type (it's implementation of IComparable<T>). The merging is stable; equal items maintain their ordering, and equal items in different collections are placed in the order of the collections.

Declaration

public static IEnumerable<T> MergeSorted<T>(params IEnumerable<T>[] collections)
    where T : IComparable<T>

Parameters

Type	Name	Description
System.Collections.Generic.IEnumerable<T>[]	collections	The set of collections to merge. In many languages, this parameter can be specified as several individual parameters.

Returns

Type	Description
System.Collections.Generic.IEnumerable<T>	An IEnumerable<T> that enumerates all the items in all the collections in sorted order.

Type Parameters

Name	Description
T

MergeSorted<T>(Comparison<T>, IEnumerable<T>[])

Merge several sorted collections into a single sorted collection. Each input collection must be sorted by the ordering in the passed Comparison<T> delegate. The merging is stable; equal items maintain their ordering, and equal items in different collections are placed in the order of the collections.

Declaration

public static IEnumerable<T> MergeSorted<T>(Comparison<T> comparison, params IEnumerable<T>[] collections)

Parameters

Type	Name	Description
System.Comparison<T>	comparison	The comparison delegate used to sort the collections.
System.Collections.Generic.IEnumerable<T>[]	collections	The set of collections to merge. In many languages, this parameter can be specified as several individual parameters.

Returns

Type	Description
System.Collections.Generic.IEnumerable<T>	An IEnumerable<T> that enumerates all the items in all the collections in sorted order.

Type Parameters

Name	Description
T

Minimum<T>(IEnumerable<T>)

Finds the minimum value in a collection.

Declaration

public static T Minimum<T>(IEnumerable<T> collection)
    where T : IComparable<T>

Parameters

Type	Name	Description
System.Collections.Generic.IEnumerable<T>	collection	The collection to search.

Returns

Type	Description
T	The smallest item in the collection.

Type Parameters

Name	Description
T	The type of items in the collection.

Remarks

Values in the collection are compared by using the IComparable<T> interfaces implementation on the type T.

Exceptions

Type	Condition
System.InvalidOperationException	The collection is empty.
System.ArgumentNullException	collection is null.

Minimum<T>(IEnumerable<T>, IComparer<T>)

Finds the minimum value in a collection. A supplied IComparer<T> is used to compare the items in the collection.

Declaration

public static T Minimum<T>(IEnumerable<T> collection, IComparer<T> comparer)

Parameters

Type	Name	Description
System.Collections.Generic.IEnumerable<T>	collection	The collection to search.
System.Collections.Generic.IComparer<T>	comparer	The comparer instance used to compare items in the collection.

Returns

Type	Description
T	The smallest item in the collection.

Type Parameters

Name	Description
T	The type of items in the collection.

Exceptions

Type	Condition
System.InvalidOperationException	The collection is empty.
System.ArgumentNullException	collection or comparer is null.

Minimum<T>(IEnumerable<T>, Comparison<T>)

Finds the minimum value in a collection. A supplied Comparison<T> delegate is used to compare the items in the collection.

Declaration

public static T Minimum<T>(IEnumerable<T> collection, Comparison<T> comparison)

Parameters

Type	Name	Description
System.Collections.Generic.IEnumerable<T>	collection	The collection to search.
System.Comparison<T>	comparison	The comparison used to compare items in the collection.

Returns

Type	Description
T	The smallest item in the collection.

Type Parameters

Name	Description
T	The type of items in the collection.

Exceptions

Type	Condition
System.InvalidOperationException	The collection is empty.
System.ArgumentNullException	collection or comparison is null.

NCopiesOf<T>(Int32, T)

Creates an IEnumerator that enumerates a given item n times.

Declaration

public static IEnumerable<T> NCopiesOf<T>(int n, T item)

Parameters

Type	Name	Description
System.Int32	n	The number of times to enumerate the item.
T	item	The item that should occur in the enumeration.

Returns

Type	Description
System.Collections.Generic.IEnumerable<T>	An IEnumerable<T> that yields n copies of item.

Type Parameters

Name	Description
T

Examples

The following creates a list consisting of 1000 copies of the double 1.0.

List<double> list = new List<double>(Algorithms.NCopiesOf(1000, 1.0));

Exceptions

Type	Condition
System.ArgumentOutOfRangeException	The argument n is less than zero.

Partition<T>(IList<T>, Predicate<T>)

Partition a list or array based on a predicate. After partitioning, all items for which the predicate returned true precede all items for which the predicate returned false.

Declaration

public static int Partition<T>(IList<T> list, Predicate<T> predicate)

Parameters

Type	Name	Description
System.Collections.Generic.IList<T>	list	The list or array to partition.
System.Predicate<T>	predicate	A delegate that defines the partitioning condition.

Returns

Type	Description
System.Int32	The index of the first item in the second half of the partition; i.e., the first item for which predicate returned false. If the predicate was true for all items in the list, list.Count is returned.

Type Parameters

Name	Description
T

Remarks

Although arrays cast to IList<T> are normally read-only, this method will work correctly and modify an array passed as list.

RandomShuffle<T>(IEnumerable<T>)

Randomly shuffles the items in a collection, yielding a new collection.

Declaration

public static T[] RandomShuffle<T>(IEnumerable<T> collection)

Parameters

Type	Name	Description
System.Collections.Generic.IEnumerable<T>	collection	The collection to shuffle.

Returns

Type	Description
T[]	An array with the same size and items as collection, but the items in a randomly chosen order.

Type Parameters

Name	Description
T	The type of the items in the collection.

RandomShuffle<T>(IEnumerable<T>, Random)

Randomly shuffles the items in a collection, yielding a new collection.

Declaration

public static T[] RandomShuffle<T>(IEnumerable<T> collection, Random randomGenerator)

Parameters

Type	Name	Description
System.Collections.Generic.IEnumerable<T>	collection	The collection to shuffle.
System.Random	randomGenerator	The random number generator to use to select the random order.

Returns

Type	Description
T[]	An array with the same size and items as collection, but the items in a randomly chosen order.

Type Parameters

Name	Description
T	The type of the items in the collection.

RandomShuffleInPlace<T>(IList<T>)

Randomly shuffles the items in a list or array, in place.

Declaration

public static void RandomShuffleInPlace<T>(IList<T> list)

Parameters

Type	Name	Description
System.Collections.Generic.IList<T>	list	The list or array to shuffle.

Type Parameters

Name	Description
T

Remarks

Although arrays cast to IList<T> are normally read-only, this method will work correctly and modify an array passed as list.

RandomShuffleInPlace<T>(IList<T>, Random)

Randomly shuffles the items in a list or array, in place.

Declaration

public static void RandomShuffleInPlace<T>(IList<T> list, Random randomGenerator)

Parameters

Type	Name	Description
System.Collections.Generic.IList<T>	list	The list or array to shuffle.
System.Random	randomGenerator	The random number generator to use to select the random order.

Type Parameters

Name	Description
T

Remarks

Although arrays cast to IList<T> are normally read-only, this method will work correctly and modify an array passed as list.

RandomSubset<T>(IEnumerable<T>, Int32)

Picks a random subset of count items from collection, and places those items into a random order. No item is selected more than once.

Declaration

public static T[] RandomSubset<T>(IEnumerable<T> collection, int count)

Parameters

Type	Name	Description
System.Collections.Generic.IEnumerable<T>	collection	The collection of items to select from. This collection is not changed.
System.Int32	count	The number of items in the subset to choose.

Returns

Type	Description
T[]	An array of count items, selected at random from collection.

Type Parameters

Name	Description
T	The type of items in the collection.

Remarks

If the collection implements IList<T>, then this method takes time O(count). Otherwise, this method takes time O(N), where N is the number of items in the collection.

Exceptions

Type	Condition
System.ArgumentOutOfRangeException	count is negative or greater than collection.Count.

RandomSubset<T>(IEnumerable<T>, Int32, Random)

Picks a random subset of count items from collection, and places those items into a random order. No item is selected more than once.

Declaration

public static T[] RandomSubset<T>(IEnumerable<T> collection, int count, Random randomGenerator)

Parameters

Type	Name	Description
System.Collections.Generic.IEnumerable<T>	collection	The collection of items to select from. This collection is not changed.
System.Int32	count	The number of items in the subset to choose.
System.Random	randomGenerator	The random number generates used to make the selection.

Returns

Type	Description
T[]	An array of count items, selected at random from collection.

Type Parameters

Name	Description
T	The type of items in the collection.

Remarks

If the collection implements IList<T>, then this method takes time O(count). Otherwise, this method takes time O(N), where N is the number of items in the collection.

Exceptions

Type	Condition
System.ArgumentOutOfRangeException	count is negative or greater than list.Count.
System.ArgumentNullException	randomGenerator is null.

Range<T>(T[], Int32, Int32)

Returns a view onto a sub-range of an array. Items from array are not copied; the returned IList<T> is simply a different view onto the same underlying items. Changes to array are reflected in the view, and vice versa. Insertions and deletions in the view change the size of the view. After an insertion, the last item in array "falls off the end". After a deletion, the last item in array becomes the default value (0 or null).

Declaration

public static IList<T> Range<T>(T[] array, int start, int count)

Parameters

Type	Name	Description
T[]	array	The array to view.
System.Int32	start	The starting index of the view.
System.Int32	count	The number of items in the view.

Returns

Type	Description
System.Collections.Generic.IList<T>	A list that is a view onto the given sub-array.

Type Parameters

Name	Description
T

Remarks

This method can be used to apply an algorithm to a portion of a array. For example:

Algorithms.ReverseInPlace(Algorithms.Range(array, 3, 6))

will reverse the 6 items beginning at index 3.

Exceptions

Type	Condition
System.ArgumentNullException	array is null.
System.ArgumentOutOfRangeException	start or count is negative.
System.ArgumentOutOfRangeException	start + count is greater than the size of array.

Range<T>(IList<T>, Int32, Int32)

Returns a view onto a sub-range of a list. Items from list are not copied; the returned IList<T> is simply a different view onto the same underlying items. Changes to list are reflected in the view, and vice versa. Insertions and deletions in the view change the size of the view, but insertions and deletions in the underlying list do not.

Declaration

public static IList<T> Range<T>(IList<T> list, int start, int count)

Parameters

Type	Name	Description
System.Collections.Generic.IList<T>	list	The list to view.
System.Int32	start	The starting index of the view.
System.Int32	count	The number of items in the view.

Returns

Type	Description
System.Collections.Generic.IList<T>	A list that is a view onto the given sub-list.

Type Parameters

Name	Description
T	The type of the items in the list.

Remarks

This method can be used to apply an algorithm to a portion of a list. For example:

Algorithms.ReverseInPlace(Algorithms.Range(list, 3, 6))

will reverse the 6 items beginning at index 3.

Exceptions

Type	Condition
System.ArgumentNullException	list is null.
System.ArgumentOutOfRangeException	start or count is negative.
System.ArgumentOutOfRangeException	start + count is greater than the size of list.

ReadOnly<T>(ICollection<T>)

Returns a read-only view onto a collection. The returned ICollection<T> interface only allows operations that do not change the collection: GetEnumerator, Contains, CopyTo, Count. The ReadOnly property returns false, indicating that the collection is read-only. All other methods on the interface throw a NotSupportedException.

Declaration

public static ICollection<T> ReadOnly<T>(ICollection<T> collection)

Parameters

Type	Name	Description
System.Collections.Generic.ICollection<T>	collection	The collection to wrap.

Returns

Type	Description
System.Collections.Generic.ICollection<T>	A read-only view onto collection. If collection is null, then null is returned.

Type Parameters

Name	Description
T	The type of items in the collection.

Remarks

The data in the underlying collection is not copied. If the underlying collection is changed, then the read-only view also changes accordingly.

ReadOnly<T>(IList<T>)

Returns a read-only view onto a list. The returned IList<T> interface only allows operations that do not change the list: GetEnumerator, Contains, CopyTo, Count, IndexOf, and the get accessor of the indexer. The IsReadOnly property returns true, indicating that the list is read-only. All other methods on the interface throw a NotSupportedException.

Declaration

public static IList<T> ReadOnly<T>(IList<T> list)

Parameters

Type	Name	Description
System.Collections.Generic.IList<T>	list	The list to wrap.

Returns

Type	Description
System.Collections.Generic.IList<T>	A read-only view onto list. Returns null if list is null. If list is already read-only, returns list.

Type Parameters

Name	Description
T	The type of items in the list.

Remarks

The data in the underlying list is not copied. If the underlying list is changed, then the read-only view also changes accordingly.

ReadOnly<TKey, TValue>(IDictionary<TKey, TValue>)

Returns a read-only view onto a dictionary. The returned IDictionary<TKey,TValue> interface only allows operations that do not change the dictionary. The IsReadOnly property returns true, indicating that the dictionary is read-only. All other methods on the interface throw a NotSupportedException.

Declaration

public static IDictionary<TKey, TValue> ReadOnly<TKey, TValue>(IDictionary<TKey, TValue> dictionary)

Parameters

Type	Name	Description
System.Collections.Generic.IDictionary<TKey, TValue>	dictionary	The dictionary to wrap.

Returns

Type	Description
System.Collections.Generic.IDictionary<TKey, TValue>	A read-only view onto dictionary. Returns null if dictionary is null. If dictionary is already read-only, returns dictionary.

Type Parameters

Name	Description
TKey
TValue

Remarks

The data in the underlying dictionary is not copied. If the underlying dictionary is changed, then the read-only view also changes accordingly.

ReadWriteList<T>(T[])

Creates a read-write IList<T> wrapper around an array. When an array is implicitely converted to an IList<T>, changes to the items in the array cannot be made through the interface. This method creates a read-write IList<T> wrapper on an array that can be used to make changes to the array.

Use this method when you need to pass an array to an algorithms that takes an IList<T> and that tries to modify items in the list. Algorithms in this class generally do not need this method, since they have been design to operate on arrays even when they are passed as an IList<T>.

Declaration

public static IList<T> ReadWriteList<T>(T[] array)

Parameters

Type	Name	Description
T[]	array	The array to wrap.

Returns

Type	Description
System.Collections.Generic.IList<T>	An IList<T> wrapper onto array.

Type Parameters

Name	Description
T

Remarks

Since arrays cannot be resized, inserting an item causes the last item in the array to be automatically removed. Removing an item causes the last item in the array to be replaced with a default value (0 or null). Clearing the list causes all the items to be replaced with a default value.

RemoveDuplicates<T>(IEnumerable<T>)

Remove consecutive equal items from a collection, yielding another collection. In each run of consecutive equal items in the collection, all items after the first item in the run are removed.

Declaration

public static IEnumerable<T> RemoveDuplicates<T>(IEnumerable<T> collection)

Parameters

Type	Name	Description
System.Collections.Generic.IEnumerable<T>	collection	The collection to process.

Returns

Type	Description
System.Collections.Generic.IEnumerable<T>	An new collection with the items from collection, in the same order, with consecutive duplicates removed.

Type Parameters

Name	Description
T

Remarks

The default sense of equality for T is used, as defined by T's implementation of IComparable<T>.Equals or object.Equals.

Exceptions

Type	Condition
System.ArgumentNullException	collection is null.

RemoveDuplicates<T>(IEnumerable<T>, IEqualityComparer<T>)

Remove consecutive equal items from a collection, yielding another collection. In each run of consecutive equal items in the collection, all items after the first item in the run are removed. A passed IEqualityComparer is used to determine equality.

Declaration

public static IEnumerable<T> RemoveDuplicates<T>(IEnumerable<T> collection, IEqualityComparer<T> equalityComparer)

Parameters

Type	Name	Description
System.Collections.Generic.IEnumerable<T>	collection	The collection to process.
System.Collections.Generic.IEqualityComparer<T>	equalityComparer	The IEqualityComparer<T> used to compare items for equality. Only the Equals method will be called.

Returns

Type	Description
System.Collections.Generic.IEnumerable<T>	An new collection with the items from collection, in the same order, with consecutive duplicates removed.

Type Parameters

Name	Description
T

Exceptions

Type	Condition
System.ArgumentNullException	collection or equalityComparer is null.

RemoveDuplicates<T>(IEnumerable<T>, BinaryPredicate<T>)

Remove consecutive "equal" items from a collection, yielding another collection. In each run of consecutive equal items in the collection, all items after the first item in the run are removed. The passed BinaryPredicate is used to determine if two items are "equal".

Declaration

public static IEnumerable<T> RemoveDuplicates<T>(IEnumerable<T> collection, BinaryPredicate<T> predicate)

Parameters

Type	Name	Description
System.Collections.Generic.IEnumerable<T>	collection	The collection to process.
BinaryPredicate<T>	predicate	The BinaryPredicate used to compare items for "equality". An item current is removed if predicate(first, current)==true, where first is the first item in the group of "duplicate" items.

Returns

Type	Description
System.Collections.Generic.IEnumerable<T>	An new collection with the items from collection, in the same order, with consecutive "duplicates" removed.

Type Parameters

Name	Description
T

Remarks

Since an arbitrary BinaryPredicate is passed to this function, what is being removed need not be true equality.

RemoveDuplicatesInPlace<T>(IList<T>)

Remove consecutive equal items from a list or array. In each run of consecutive equal items in the list, all items after the first item in the run are removed. The removal is done in-place, changing the list.

Declaration

public static void RemoveDuplicatesInPlace<T>(IList<T> list)

Parameters

Type	Name	Description
System.Collections.Generic.IList<T>	list	The list or array to process.

Type Parameters

Name	Description
T

Remarks

The default sense of equality for T is used, as defined by T's implementation of IComparable<T>.Equals or object.Equals.

Although arrays cast to IList<T> are normally read-only, this method will work correctly and modify an array passed as list.

RemoveDuplicatesInPlace<T>(IList<T>, IEqualityComparer<T>)

Remove subsequent consecutive equal items from a list or array. In each run of consecutive equal items in the list, all items after the first item in the run are removed. The replacement is done in-place, changing the list. A passed IEqualityComparer is used to determine equality.

Declaration

public static void RemoveDuplicatesInPlace<T>(IList<T> list, IEqualityComparer<T> equalityComparer)

Parameters

Type	Name	Description
System.Collections.Generic.IList<T>	list	The list or array to process.
System.Collections.Generic.IEqualityComparer<T>	equalityComparer	The IEqualityComparer<T> used to compare items for equality. Only the Equals method will be called.

Type Parameters

Name	Description
T

Remarks

Although arrays cast to IList<T> are normally read-only, this method will work correctly and modify an array passed as list.

RemoveDuplicatesInPlace<T>(IList<T>, BinaryPredicate<T>)

Remove consecutive "equal" items from a list or array. In each run of consecutive equal items in the list, all items after the first item in the run are removed. The replacement is done in-place, changing the list. The passed BinaryPredicate is used to determine if two items are "equal".

Declaration

public static void RemoveDuplicatesInPlace<T>(IList<T> list, BinaryPredicate<T> predicate)

Parameters

Type	Name	Description
System.Collections.Generic.IList<T>	list	The list or array to process.
BinaryPredicate<T>	predicate	The BinaryPredicate used to compare items for "equality".

Type Parameters

Name	Description
T

Remarks

Since an arbitrary BinaryPredicate is passed to this function, what is being tested for need not be true equality.

Although arrays cast to IList<T> are normally read-only, this method will work correctly and modify an array passed as list.

RemoveWhere<T>(ICollection<T>, Predicate<T>)

Removes all the items in the collection that satisfy the condition defined by predicate.

Declaration

public static ICollection<T> RemoveWhere<T>(ICollection<T> collection, Predicate<T> predicate)

Parameters

Type	Name	Description
System.Collections.Generic.ICollection<T>	collection	The collection to check all the items in.
System.Predicate<T>	predicate	A delegate that defines the condition to check for.

Returns

Type	Description
System.Collections.Generic.ICollection<T>	Returns a collection of the items that were removed. This collection contains the items in the same order that they orginally appeared in collection.

Type Parameters

Name	Description
T

Remarks

If the collection if an array or implements IList<T>, an efficient algorithm that compacts items is used. If not, then ICollection<T>.Remove is used to remove items from the collection. If the collection is an array or fixed-size list, the non-removed elements are placed, in order, at the beginning of the list, and the remaining list items are filled with a default value (0 or null).

Replace<T>(IEnumerable<T>, T, T)

Replace all items in a collection equal to a particular value with another values, yielding another collection.

Declaration

public static IEnumerable<T> Replace<T>(IEnumerable<T> collection, T itemFind, T replaceWith)

Parameters

Type	Name	Description
System.Collections.Generic.IEnumerable<T>	collection	The collection to process.
T	itemFind	The value to find and replace within collection.
T	replaceWith	The new value to replace with.

Returns

Type	Description
System.Collections.Generic.IEnumerable<T>	An new collection with the items from collection, in the same order, with the appropriate replacements made.

Type Parameters

Name	Description
T

Remarks

The default sense of equality for T is used, as defined by T's implementation of IComparable<T>.Equals or object.Equals.

Replace<T>(IEnumerable<T>, T, T, IEqualityComparer<T>)

Replace all items in a collection equal to a particular value with another values, yielding another collection. A passed IEqualityComparer is used to determine equality.

Declaration

public static IEnumerable<T> Replace<T>(IEnumerable<T> collection, T itemFind, T replaceWith, IEqualityComparer<T> equalityComparer)

Parameters

Type	Name	Description
System.Collections.Generic.IEnumerable<T>	collection	The collection to process.
T	itemFind	The value to find and replace within collection.
T	replaceWith	The new value to replace with.
System.Collections.Generic.IEqualityComparer<T>	equalityComparer	The IEqualityComparer<T> used to compare items for equality. Only the Equals method will be called.

Returns

Type	Description
System.Collections.Generic.IEnumerable<T>	An new collection with the items from collection, in the same order, with the appropriate replacements made.

Type Parameters

Name	Description
T

Replace<T>(IEnumerable<T>, Predicate<T>, T)

Replace all items in a collection that a predicate evalues at true with a value, yielding another collection. .

Declaration

public static IEnumerable<T> Replace<T>(IEnumerable<T> collection, Predicate<T> predicate, T replaceWith)

Parameters

Type	Name	Description
System.Collections.Generic.IEnumerable<T>	collection	The collection to process.
System.Predicate<T>	predicate	The predicate used to evaluate items with the collection. If the predicate returns true for a particular item, the item is replaces with replaceWith.
T	replaceWith	The new value to replace with.

Returns

Type	Description
System.Collections.Generic.IEnumerable<T>	An new collection with the items from collection, in the same order, with the appropriate replacements made.

Type Parameters

Name	Description
T

ReplaceInPlace<T>(IList<T>, T, T)

Replace all items in a list or array equal to a particular value with another value. The replacement is done in-place, changing the list.

Declaration

public static void ReplaceInPlace<T>(IList<T> list, T itemFind, T replaceWith)

Parameters

Type	Name	Description
System.Collections.Generic.IList<T>	list	The list or array to process.
T	itemFind	The value to find and replace within collection.
T	replaceWith	The new value to replace with.

Type Parameters

Name	Description
T

Remarks

The default sense of equality for T is used, as defined by T's implementation of IComparable<T>.Equals or object.Equals.

Although arrays cast to IList<T> are normally read-only, this method will work correctly and modify an array passed as list.

ReplaceInPlace<T>(IList<T>, T, T, IEqualityComparer<T>)

Replace all items in a list or array equal to a particular value with another values. The replacement is done in-place, changing the list. A passed IEqualityComparer is used to determine equality.

Declaration

public static void ReplaceInPlace<T>(IList<T> list, T itemFind, T replaceWith, IEqualityComparer<T> equalityComparer)

Parameters

Type	Name	Description
System.Collections.Generic.IList<T>	list	The list or array to process.
T	itemFind	The value to find and replace within collection.
T	replaceWith	The new value to replace with.
System.Collections.Generic.IEqualityComparer<T>	equalityComparer	The IEqualityComparer<T> used to compare items for equality. Only the Equals method will be called.

Type Parameters

Name	Description
T

Remarks

Although arrays cast to IList<T> are normally read-only, this method will work correctly and modify an array passed as list.

ReplaceInPlace<T>(IList<T>, Predicate<T>, T)

Replace all items in a list or array that a predicate evaluates at true with a value. The replacement is done in-place, changing the list.

Declaration

public static void ReplaceInPlace<T>(IList<T> list, Predicate<T> predicate, T replaceWith)

Parameters

Type	Name	Description
System.Collections.Generic.IList<T>	list	The list or array to process.
System.Predicate<T>	predicate	The predicate used to evaluate items with the collection. If the predicate returns true for a particular item, the item is replaces with replaceWith.
T	replaceWith	The new value to replace with.

Type Parameters

Name	Description
T

Remarks

Although arrays cast to IList<T> are normally read-only, this method will work correctly and modify an array passed as list.

Reverse<T>(IList<T>)

Reverses a list and returns the reversed list, without changing the source list.

Declaration

public static IEnumerable<T> Reverse<T>(IList<T> source)

Parameters

Type	Name	Description
System.Collections.Generic.IList<T>	source	The list to reverse.

Returns

Type	Description
System.Collections.Generic.IEnumerable<T>	A collection that contains the items from source in reverse order.

Type Parameters

Name	Description
T

Exceptions

Type	Condition
System.ArgumentNullException	source is null.

ReverseInPlace<T>(IList<T>)

Reverses a list or array in place.

Declaration

public static void ReverseInPlace<T>(IList<T> list)

Parameters

Type	Name	Description
System.Collections.Generic.IList<T>	list	The list or array to reverse.

Type Parameters

Name	Description
T

Remarks

Although arrays cast to IList<T> are normally read-only, this method will work correctly and modify an array passed as list.

Exceptions

Type	Condition
System.ArgumentNullException	list is null.
System.ArgumentException	list is read only.

Rotate<T>(IList<T>, Int32)

Rotates a list and returns the rotated list, without changing the source list.

Declaration

public static IEnumerable<T> Rotate<T>(IList<T> source, int amountToRotate)

Parameters

Type	Name	Description
System.Collections.Generic.IList<T>	source	The list to rotate.
System.Int32	amountToRotate	The number of elements to rotate. This value can be positive or negative. For example, rotating by positive 3 means that source[3] is the first item in the returned collection. Rotating by negative 3 means that source[source.Count - 3] is the first item in the returned collection.

Returns

Type	Description
System.Collections.Generic.IEnumerable<T>	A collection that contains the items from source in rotated order.

Type Parameters

Name	Description
T

Exceptions

Type	Condition
System.ArgumentNullException	source is null.

RotateInPlace<T>(IList<T>, Int32)

Rotates a list or array in place.

Declaration

public static void RotateInPlace<T>(IList<T> list, int amountToRotate)

Parameters

Type	Name	Description
System.Collections.Generic.IList<T>	list	The list or array to rotate.
System.Int32	amountToRotate	The number of elements to rotate. This value can be positive or negative. For example, rotating by positive 3 means that list[3] is the first item in the resulting list. Rotating by negative 3 means that list[list.Count - 3] is the first item in the resulting list.

Type Parameters

Name	Description
T

Remarks

Although arrays cast to IList<T> are normally read-only, this method will work correctly and modify an array passed as list.

Exceptions

Type	Condition
System.ArgumentNullException	list is null.

SearchForSubsequence<T>(IList<T>, IEnumerable<T>)

Searchs a list for a sub-sequence of items that match a particular pattern. A subsequence of list matches pattern at index i if list[i] is equal to the first item in pattern, list[i+1] is equal to the second item in pattern, and so forth for all the items in pattern.

Declaration

public static int SearchForSubsequence<T>(IList<T> list, IEnumerable<T> pattern)

Parameters

Type	Name	Description
System.Collections.Generic.IList<T>	list	The list to search.
System.Collections.Generic.IEnumerable<T>	pattern	The sequence of items to search for.

Returns

Type	Description
System.Int32	The first index with list that matches the items in pattern.

Type Parameters

Name	Description
T	The type of items in the list.

Remarks

The default sense of equality for T is used, as defined by T's implementation of IComparable<T>.Equals or object.Equals.

SearchForSubsequence<T>(IList<T>, IEnumerable<T>, IEqualityComparer<T>)

Searchs a list for a sub-sequence of items that match a particular pattern. A subsequence of list matches pattern at index i if list[i] is equal to the first item in pattern, list[i+1] is equal to the second item in pattern, and so forth for all the items in pattern. The passed instance of IEqualityComparer<T> is used for determining if two items are equal.

Declaration

public static int SearchForSubsequence<T>(IList<T> list, IEnumerable<T> pattern, IEqualityComparer<T> equalityComparer)

Parameters

Type	Name	Description
System.Collections.Generic.IList<T>	list	The list to search.
System.Collections.Generic.IEnumerable<T>	pattern	The sequence of items to search for.
System.Collections.Generic.IEqualityComparer<T>	equalityComparer	The IEqualityComparer<T> used to compare items for equality. Only the Equals method will be called.

Returns

Type	Description
System.Int32	The first index with list that matches the items in pattern.

Type Parameters

Name	Description
T	The type of items in the list.

SearchForSubsequence<T>(IList<T>, IEnumerable<T>, BinaryPredicate<T>)

Searchs a list for a sub-sequence of items that match a particular pattern. A subsequence of list matches pattern at index i if list[i] is "equal" to the first item in pattern, list[i+1] is "equal" to the second item in pattern, and so forth for all the items in pattern. The passed BinaryPredicate is used to determine if two items are "equal".

Declaration

public static int SearchForSubsequence<T>(IList<T> list, IEnumerable<T> pattern, BinaryPredicate<T> predicate)

Parameters

Type	Name	Description
System.Collections.Generic.IList<T>	list	The list to search.
System.Collections.Generic.IEnumerable<T>	pattern	The sequence of items to search for.
BinaryPredicate<T>	predicate	The BinaryPredicate used to compare items for "equality".

Returns

Type	Description
System.Int32	The first index with list that matches the items in pattern.

Type Parameters

Name	Description
T	The type of items in the list.

Remarks

Since an arbitrary BinaryPredicate is passed to this function, what is being tested for in the pattern need not be equality.

SetDifference<T>(IEnumerable<T>, IEnumerable<T>)

Computes the set-theoretic difference of two collections. The difference of two sets is all items that appear in the first set, but not in the second. If an item appears X times in the first set, and Y times in the second set, the difference contains the item X - Y times (0 times if X < Y). The source collections are not changed. A new collection is created with the difference of the collections; the order of the items in this collection is undefined.

Declaration

public static IEnumerable<T> SetDifference<T>(IEnumerable<T> collection1, IEnumerable<T> collection2)

Parameters

Type	Name	Description
System.Collections.Generic.IEnumerable<T>	collection1	The first collection to difference.
System.Collections.Generic.IEnumerable<T>	collection2	The second collection to difference.

Returns

Type	Description
System.Collections.Generic.IEnumerable<T>	The difference of collection1 and collection2, considered as sets.

Type Parameters

Name	Description
T

Remarks

When equal items appear in both collections, the returned collection will include an arbitrary choice of one of the two equal items.

The default sense of equality for T is used, as defined by T's implementation of IComparable<T>.Equals or object.Equals.

If both collections are Set, Bag, OrderedSet, or OrderedBag collections, it is more efficient to use the Difference or DifferenceWith methods on that class.

Exceptions

Type	Condition
System.ArgumentNullException	collection1 or collection2 is null.

SetDifference<T>(IEnumerable<T>, IEnumerable<T>, IEqualityComparer<T>)

Computes the set-theoretic difference of two collections. The difference of two sets is all items that appear in the first set, but not in the second. If an item appears X times in the first set, and Y times in the second set, the difference contains the item X - Y times (0 times if X < Y). The source collections are not changed. A new collection is created with the difference of the collections; the order of the items in this collection is undefined.

Declaration

public static IEnumerable<T> SetDifference<T>(IEnumerable<T> collection1, IEnumerable<T> collection2, IEqualityComparer<T> equalityComparer)

Parameters

Type	Name	Description
System.Collections.Generic.IEnumerable<T>	collection1	The first collection to difference.
System.Collections.Generic.IEnumerable<T>	collection2	The second collection to difference.
System.Collections.Generic.IEqualityComparer<T>	equalityComparer	The IEqualityComparer<T> used to compare items for equality. Only the Equals and GetHashCode member functions of this interface are called.

Returns

Type	Description
System.Collections.Generic.IEnumerable<T>	The difference of collection1 and collection2, considered as sets.

Type Parameters

Name	Description
T

Remarks

When equal items appear in both collections, the returned collection will include an arbitrary choice of one of the two equal items.

If both collections are Set, Bag, OrderedSet, or OrderedBag collections, it is more efficient to use the difference or differenceWith methods on that class.

Exceptions

Type	Condition
System.ArgumentNullException	collection1 or collection2 is null.

SetIntersection<T>(IEnumerable<T>, IEnumerable<T>)

Computes the set-theoretic intersection of two collections. The intersection of two sets is all items that appear in both of the sets. If an item appears X times in one set, and Y times in the other set, the intersection contains the item Minimum(X,Y) times. The source collections are not changed. A new collection is created with the intersection of the collections; the order of the items in this collection is undefined.

Declaration

public static IEnumerable<T> SetIntersection<T>(IEnumerable<T> collection1, IEnumerable<T> collection2)

Parameters

Type	Name	Description
System.Collections.Generic.IEnumerable<T>	collection1	The first collection to intersect.
System.Collections.Generic.IEnumerable<T>	collection2	The second collection to intersect.

Returns

Type	Description
System.Collections.Generic.IEnumerable<T>	The intersection of the two collections, considered as sets.

Type Parameters

Name	Description
T

Remarks

When equal items appear in both collections, the returned collection will include an arbitrary choice of one of the two equal items.

The default sense of equality for T is used, as defined by T's implementation of IComparable<T>.Equals or object.Equals.

If both collections are Set, Bag, OrderedSet, or OrderedBag collections, it is more efficient to use the Intersection or IntersectionWith methods on that class.

Exceptions

Type	Condition
System.ArgumentNullException	collection1 or collection2 is null.

SetIntersection<T>(IEnumerable<T>, IEnumerable<T>, IEqualityComparer<T>)

Computes the set-theoretic intersection of two collections. The intersection of two sets is all items that appear in both of the sets. If an item appears X times in one set, and Y times in the other set, the intersection contains the item Minimum(X,Y) times. The source collections are not changed. A new collection is created with the intersection of the collections; the order of the items in this collection is undefined.

Declaration

public static IEnumerable<T> SetIntersection<T>(IEnumerable<T> collection1, IEnumerable<T> collection2, IEqualityComparer<T> equalityComparer)

Parameters

Type	Name	Description
System.Collections.Generic.IEnumerable<T>	collection1	The first collection to intersect.
System.Collections.Generic.IEnumerable<T>	collection2	The second collection to intersect.
System.Collections.Generic.IEqualityComparer<T>	equalityComparer	The IEqualityComparer<T> used to compare items for equality. Only the Equals and GetHashCode member functions of this interface are called.

Returns

Type	Description
System.Collections.Generic.IEnumerable<T>	The intersection of the two collections, considered as sets.

Type Parameters

Name	Description
T

Remarks

When equal items appear in both collections, the returned collection will include an arbitrary choice of one of the two equal items.

If both collections are Set, Bag, OrderedSet, or OrderedBag collections, it is more efficient to use the Intersection or IntersectionWith methods on that class.

Exceptions

Type	Condition
System.ArgumentNullException	collection1 or collection2 is null.

SetSymmetricDifference<T>(IEnumerable<T>, IEnumerable<T>)

Computes the set-theoretic symmetric difference of two collections. The symmetric difference of two sets is all items that appear in the one of the sets, but not in the other. If an item appears X times in the one set, and Y times in the other set, the symmetric difference contains the item AbsoluteValue(X - Y) times. The source collections are not changed. A new collection is created with the symmetric difference of the collections; the order of the items in this collection is undefined.

Declaration

public static IEnumerable<T> SetSymmetricDifference<T>(IEnumerable<T> collection1, IEnumerable<T> collection2)

Parameters

Type	Name	Description
System.Collections.Generic.IEnumerable<T>	collection1	The first collection to symmetric difference.
System.Collections.Generic.IEnumerable<T>	collection2	The second collection to symmetric difference.

Returns

Type	Description
System.Collections.Generic.IEnumerable<T>	The symmetric difference of collection1 and collection2, considered as sets.

Type Parameters

Name	Description
T

Remarks

When equal items appear in both collections, the returned collection will include an arbitrary choice of one of the two equal items.

The default sense of equality for T is used, as defined by T's implementation of IComparable<T>.Equals or object.Equals.

If both collections are Set, Bag, OrderedSet, or OrderedBag collections, it is more efficient to use the SymmetricDifference or SymmetricDifferenceWith methods on that class.

Exceptions

Type	Condition
System.ArgumentNullException	collection1 or collection2 is null.

SetSymmetricDifference<T>(IEnumerable<T>, IEnumerable<T>, IEqualityComparer<T>)

Computes the set-theoretic symmetric difference of two collections. The symmetric difference of two sets is all items that appear in the one of the sets, but not in the other. If an item appears X times in the one set, and Y times in the other set, the symmetric difference contains the item AbsoluteValue(X - Y) times. The source collections are not changed. A new collection is created with the symmetric difference of the collections; the order of the items in this collection is undefined.

Declaration

public static IEnumerable<T> SetSymmetricDifference<T>(IEnumerable<T> collection1, IEnumerable<T> collection2, IEqualityComparer<T> equalityComparer)

Parameters

Type	Name	Description
System.Collections.Generic.IEnumerable<T>	collection1	The first collection to symmetric difference.
System.Collections.Generic.IEnumerable<T>	collection2	The second collection to symmetric difference.
System.Collections.Generic.IEqualityComparer<T>	equalityComparer	The IEqualityComparer<T> used to compare items for equality. Only the Equals and GetHashCode member functions of this interface are called.

Returns

Type	Description
System.Collections.Generic.IEnumerable<T>	The symmetric difference of collection1 and collection2, considered as sets.

Type Parameters

Name	Description
T

Remarks

When equal items appear in both collections, the returned collection will include an arbitrary choice of one of the two equal items.

If both collections are Set, Bag, OrderedSet, or OrderedBag collections, it is more efficient to use the symmetric difference or symmetric differenceWith methods on that class.

Exceptions

Type	Condition
System.ArgumentNullException	collection1 or collection2 is null.

SetUnion<T>(IEnumerable<T>, IEnumerable<T>)

Computes the set-theoretic union of two collections. The union of two sets is all items that appear in either of the sets. If an item appears X times in one set, and Y times in the other set, the union contains the item Maximum(X,Y) times. The source collections are not changed. A new collection is created with the union of the collections; the order of the items in this collection is undefined.

Declaration

public static IEnumerable<T> SetUnion<T>(IEnumerable<T> collection1, IEnumerable<T> collection2)

Parameters

Type	Name	Description
System.Collections.Generic.IEnumerable<T>	collection1	The first collection to union.
System.Collections.Generic.IEnumerable<T>	collection2	The second collection to union.

Returns

Type	Description
System.Collections.Generic.IEnumerable<T>	The union of the two collections, considered as sets.

Type Parameters

Name	Description
T

Remarks

When equal items appear in both collections, the returned collection will include an arbitrary choice of one of the two equal items.

The default sense of equality for T is used, as defined by T's implementation of IComparable<T>.Equals or object.Equals.

If both collections are Set, Bag, OrderedSet, or OrderedBag collections, it is more efficient to use the Union or UnionWith methods on that class.

Exceptions

Type	Condition
System.ArgumentNullException	collection1 or collection2 is null.

SetUnion<T>(IEnumerable<T>, IEnumerable<T>, IEqualityComparer<T>)

Computes the set-theoretic union of two collections. The union of two sets is all items that appear in either of the sets. If an item appears X times in one set, and Y times in the other set, the union contains the item Maximum(X,Y) times. The source collections are not changed. A new collection is created with the union of the collections; the order of the items in this collection is undefined.

Declaration

public static IEnumerable<T> SetUnion<T>(IEnumerable<T> collection1, IEnumerable<T> collection2, IEqualityComparer<T> equalityComparer)

Parameters

Type	Name	Description
System.Collections.Generic.IEnumerable<T>	collection1	The first collection to union.
System.Collections.Generic.IEnumerable<T>	collection2	The second collection to union.
System.Collections.Generic.IEqualityComparer<T>	equalityComparer	The IEqualityComparer<T> used to compare items for equality. Only the Equals and GetHashCode member functions of this interface are called.

Returns

Type	Description
System.Collections.Generic.IEnumerable<T>	The union of the two collections, considered as sets.

Type Parameters

Name	Description
T

Remarks

When equal items appear in both collections, the returned collection will include an arbitrary choice of one of the two equal items.

If both collections are Set, Bag, OrderedSet, or OrderedBag collections, it is more efficient to use the union or unionWith methods on that class.

Exceptions

Type	Condition
System.ArgumentNullException	collection1 or collection2 is null.

Sort<T>(IEnumerable<T>)

Creates a sorted version of a collection.

Declaration

public static T[] Sort<T>(IEnumerable<T> collection)
    where T : IComparable<T>

Parameters

Type	Name	Description
System.Collections.Generic.IEnumerable<T>	collection	The collection to sort.

Returns

Type	Description
T[]	An array containing the sorted version of the collection.

Type Parameters

Name	Description
T

Remarks

Values are compared by using the IComparable<T> interfaces implementation on the type T.

Sort<T>(IEnumerable<T>, IComparer<T>)

Creates a sorted version of a collection. A supplied IComparer<T> is used to compare the items in the collection.

Declaration

public static T[] Sort<T>(IEnumerable<T> collection, IComparer<T> comparer)

Parameters

Type	Name	Description
System.Collections.Generic.IEnumerable<T>	collection	The collection to sort.
System.Collections.Generic.IComparer<T>	comparer	The comparer instance used to compare items in the collection. Only the Compare method is used.

Returns

Type	Description
T[]	An array containing the sorted version of the collection.

Type Parameters

Name	Description
T

Sort<T>(IEnumerable<T>, Comparison<T>)

Creates a sorted version of a collection. A supplied Comparison<T> delegate is used to compare the items in the collection.

Declaration

public static T[] Sort<T>(IEnumerable<T> collection, Comparison<T> comparison)

Parameters

Type	Name	Description
System.Collections.Generic.IEnumerable<T>	collection	The collection to sort.
System.Comparison<T>	comparison	The comparison delegate used to compare items in the collection.

Returns

Type	Description
T[]	An array containing the sorted version of the collection.

Type Parameters

Name	Description
T

SortInPlace<T>(IList<T>)

Sorts a list or array in place.

Declaration

public static void SortInPlace<T>(IList<T> list)
    where T : IComparable<T>

Parameters

Type	Name	Description
System.Collections.Generic.IList<T>	list	The list or array to sort.

Type Parameters

Name	Description
T

Remarks

The Quicksort algorithms is used to sort the items. In virtually all cases, this takes time O(N log N), where N is the number of items in the list.

Values are compared by using the IComparable<T> interfaces implementation on the type T.

Although arrays cast to IList<T> are normally read-only, this method will work correctly and modify an array passed as list.

SortInPlace<T>(IList<T>, IComparer<T>)

Sorts a list or array in place. A supplied IComparer<T> is used to compare the items in the list.

Declaration

public static void SortInPlace<T>(IList<T> list, IComparer<T> comparer)

Parameters

Type	Name	Description
System.Collections.Generic.IList<T>	list	The list or array to sort.
System.Collections.Generic.IComparer<T>	comparer	The comparer instance used to compare items in the collection. Only the Compare method is used.

Type Parameters

Name	Description
T

Remarks

The Quicksort algorithms is used to sort the items. In virtually all cases, this takes time O(N log N), where N is the number of items in the list.

Although arrays cast to IList<T> are normally read-only, this method will work correctly and modify an array passed as list.

SortInPlace<T>(IList<T>, Comparison<T>)

Sorts a list or array in place. A supplied Comparison<T> delegate is used to compare the items in the list.

Declaration

public static void SortInPlace<T>(IList<T> list, Comparison<T> comparison)

Parameters

Type	Name	Description
System.Collections.Generic.IList<T>	list	The list or array to sort.
System.Comparison<T>	comparison	The comparison delegate used to compare items in the collection.

Type Parameters

Name	Description
T

Remarks

The Quicksort algorithms is used to sort the items. In virtually all cases, this takes time O(N log N), where N is the number of items in the list.

Although arrays cast to IList<T> are normally read-only, this method will work correctly and modify an array passed as list.

StablePartition<T>(IList<T>, Predicate<T>)

Partition a list or array based on a predicate. After partitioning, all items for which the predicate returned true precede all items for which the predicate returned false. The partition is stable, which means that if items X and Y have the same result from the predicate, and X precedes Y in the original list, X will precede Y in the partitioned list.

Declaration

public static int StablePartition<T>(IList<T> list, Predicate<T> predicate)

Parameters

Type	Name	Description
System.Collections.Generic.IList<T>	list	The list or array to partition.
System.Predicate<T>	predicate	A delegate that defines the partitioning condition.

Returns

Type	Description
System.Int32	The index of the first item in the second half of the partition; i.e., the first item for which predicate returned false. If the predicate was true for all items in the list, list.Count is returned.

Type Parameters

Name	Description
T

Remarks

Although arrays cast to IList<T> are normally read-only, this method will work correctly and modify an array passed as list.

StableSort<T>(IEnumerable<T>)

Creates a sorted version of a collection. The sort is stable, which means that if items X and Y are equal, and X precedes Y in the unsorted collection, X will precede Y is the sorted collection.

Declaration

public static T[] StableSort<T>(IEnumerable<T> collection)
    where T : IComparable<T>

Parameters

Type	Name	Description
System.Collections.Generic.IEnumerable<T>	collection	The collection to sort.

Returns

Type	Description
T[]	An array containing the sorted version of the collection.

Type Parameters

Name	Description
T

Remarks

Values are compared by using the IComparable<T> interfaces implementation on the type T.

StableSort<T>(IEnumerable<T>, IComparer<T>)

Creates a sorted version of a collection. The sort is stable, which means that if items X and Y are equal, and X precedes Y in the unsorted collection, X will precede Y is the sorted collection. A supplied IComparer<T> is used to compare the items in the collection.

Declaration

public static T[] StableSort<T>(IEnumerable<T> collection, IComparer<T> comparer)

Parameters

Type	Name	Description
System.Collections.Generic.IEnumerable<T>	collection	The collection to sort.
System.Collections.Generic.IComparer<T>	comparer	The comparer instance used to compare items in the collection. Only the Compare method is used.

Returns

Type	Description
T[]	An array containing the sorted version of the collection.

Type Parameters

Name	Description
T

StableSort<T>(IEnumerable<T>, Comparison<T>)

Creates a sorted version of a collection. The sort is stable, which means that if items X and Y are equal, and X precedes Y in the unsorted collection, X will precede Y is the sorted collection. A supplied Comparison<T> delegate is used to compare the items in the collection.

Declaration

public static T[] StableSort<T>(IEnumerable<T> collection, Comparison<T> comparison)

Parameters

Type	Name	Description
System.Collections.Generic.IEnumerable<T>	collection	The collection to sort.
System.Comparison<T>	comparison	The comparison delegate used to compare items in the collection.

Returns

Type	Description
T[]	An array containing the sorted version of the collection.

Type Parameters

Name	Description
T

Remarks

Values are compared by using the IComparable<T> interfaces implementation on the type T.

StableSortInPlace<T>(IList<T>)

Sorts a list or array in place. The sort is stable, which means that if items X and Y are equal, and X precedes Y in the unsorted collection, X will precede Y is the sorted collection.

Declaration

public static void StableSortInPlace<T>(IList<T> list)
    where T : IComparable<T>

Parameters

Type	Name	Description
System.Collections.Generic.IList<T>	list	The list or array to sort.

Type Parameters

Name	Description
T

Remarks

Values are compared by using the IComparable<T> interfaces implementation on the type T.

Although arrays cast to IList<T> are normally read-only, this method will work correctly and modify an array passed as list.

StableSortInPlace<T>(IList<T>, IComparer<T>)

Sorts a list or array in place. The sort is stable, which means that if items X and Y are equal, and X precedes Y in the unsorted collection, X will precede Y is the sorted collection. A supplied IComparer<T> is used to compare the items in the list.

Declaration

public static void StableSortInPlace<T>(IList<T> list, IComparer<T> comparer)

Parameters

Type	Name	Description
System.Collections.Generic.IList<T>	list	The list or array to sort.
System.Collections.Generic.IComparer<T>	comparer	The comparer instance used to compare items in the collection. Only the Compare method is used.

Type Parameters

Name	Description
T

Remarks

Although arrays cast to IList<T> are normally read-only, this method will work correctly and modify an array passed as list.

StableSortInPlace<T>(IList<T>, Comparison<T>)

Sorts a list or array in place. The sort is stable, which means that if items X and Y are equal, and X precedes Y in the unsorted collection, X will precede Y is the sorted collection. A supplied Comparison<T> delegate is used to compare the items in the list.

Declaration

public static void StableSortInPlace<T>(IList<T> list, Comparison<T> comparison)

Parameters

Type	Name	Description
System.Collections.Generic.IList<T>	list	The list or array to sort.
System.Comparison<T>	comparison	The comparison delegate used to compare items in the collection.

Type Parameters

Name	Description
T

Remarks

Although arrays cast to IList<T> are normally read-only, this method will work correctly and modify an array passed as list.

ToArray<T>(IEnumerable<T>)

Create an array with the items in a collection.

Declaration

public static T[] ToArray<T>(IEnumerable<T> collection)

Parameters

Type	Name	Description
System.Collections.Generic.IEnumerable<T>	collection	Collection to create array from.

Returns

Type	Description
T[]	An array with the items from the collection, in enumeration order.

Type Parameters

Name	Description
T	Element type of the collection.

Remarks

If collection implements ICollection<T>T, then ICollection<T>.CopyTo() is used to fill the array. Otherwise, the IEnumerable<T>.GetEnumerator() is used to fill the array.

Exceptions

Type	Condition
System.ArgumentNullException	collection is null.

ToString<T>(IEnumerable<T>)

Gets a string representation of the elements in the collection. The string representation starts with "{", has a list of items separated by commas (","), and ends with "}". Each item in the collection is converted to a string by calling its ToString method (null is represented by "null"). Contained collections (except strings) are recursively converted to strings by this method.

Declaration

public static string ToString<T>(IEnumerable<T> collection)

Parameters

Type	Name	Description
System.Collections.Generic.IEnumerable<T>	collection	A collection to get the string representation of.

Returns

Type	Description
System.String	The string representation of the collection. If collection is null, then the string "null" is returned.

Type Parameters

Name	Description
T

ToString<T>(IEnumerable<T>, Boolean, String, String, String)

Gets a string representation of the elements in the collection. The string to used at the beginning and end, and to separate items, and supplied by parameters. Each item in the collection is converted to a string by calling its ToString method (null is represented by "null").

Declaration

public static string ToString<T>(IEnumerable<T> collection, bool recursive, string start, string separator, string end)

Parameters

Type	Name	Description
System.Collections.Generic.IEnumerable<T>	collection	A collection to get the string representation of.
System.Boolean	recursive	If true, contained collections (except strings) are converted to strings by a recursive call to this method, instead of by calling ToString.
System.String	start	The string to appear at the beginning of the output string.
System.String	separator	The string to appear between each item in the string.
System.String	end	The string to appear at the end of the output string.

Returns

Type	Description
System.String	The string representation of the collection. If collection is null, then the string "null" is returned.

Type Parameters

Name	Description
T

Exceptions

Type	Condition
System.ArgumentNullException	start, separator, or end is null.

ToString<TKey, TValue>(IDictionary<TKey, TValue>)

Gets a string representation of the mappings in a dictionary. The string representation starts with "{", has a list of mappings separated by commas (", "), and ends with "}". Each mapping is represented by "key->value". Each key and value in the dictionary is converted to a string by calling its ToString method (null is represented by "null"). Contained collections (except strings) are recursively converted to strings by this method.

Declaration

public static string ToString<TKey, TValue>(IDictionary<TKey, TValue> dictionary)

Parameters

Type	Name	Description
System.Collections.Generic.IDictionary<TKey, TValue>	dictionary	A dictionary to get the string representation of.

Returns

Type	Description
System.String	The string representation of the collection, or "null" if dictionary is null.

Type Parameters

Name	Description
TKey
TValue

TrueForAll<T>(IEnumerable<T>, Predicate<T>)

Determines if all of the items in the collection satisfy the condition defined by predicate.

Declaration

public static bool TrueForAll<T>(IEnumerable<T> collection, Predicate<T> predicate)

Parameters

Type	Name	Description
System.Collections.Generic.IEnumerable<T>	collection	The collection to check all the items in.
System.Predicate<T>	predicate	A delegate that defines the condition to check for.

Returns

Type	Description
System.Boolean	True if all of the items in the collection satisfy the condition defined by predicate, or if the collection is empty. False if one or more items in the collection do not satisfy predicate.

Type Parameters

Name	Description
T

TryFindFirstWhere<T>(IEnumerable<T>, Predicate<T>, out T)

Finds the first item in a collection that satisfies the condition defined by predicate.

Declaration

public static bool TryFindFirstWhere<T>(IEnumerable<T> collection, Predicate<T> predicate, out T foundItem)

Parameters

Type	Name	Description
System.Collections.Generic.IEnumerable<T>	collection	The collection to search.
System.Predicate<T>	predicate	A delegate that defined the condition to check for.
T	foundItem	Outputs the first item in the collection that matches the condition, if the method returns true.

Returns

Type	Description
System.Boolean	True if an item satisfying the condition was found. False if no such item exists in the collection.

Type Parameters

Name	Description
T

See Also

FindFirstWhere<T>(IEnumerable<T>, Predicate<T>)

TryFindLastWhere<T>(IEnumerable<T>, Predicate<T>, out T)

Finds the last item in a collection that satisfies the condition defined by predicate.

Declaration

public static bool TryFindLastWhere<T>(IEnumerable<T> collection, Predicate<T> predicate, out T foundItem)

Parameters

Type	Name	Description
System.Collections.Generic.IEnumerable<T>	collection	The collection to search.
System.Predicate<T>	predicate	A delegate that defined the condition to check for.
T	foundItem	Outputs the last item in the collection that matches the condition, if the method returns true.

Returns

Type	Description
System.Boolean	True if an item satisfying the condition was found. False if no such item exists in the collection.

Type Parameters

Name	Description
T

Remarks

If the collection implements IList<T>, then the list is scanned in reverse until a matching item is found. Otherwise, the entire collection is iterated in the forward direction.

See Also

FindLastWhere<T>(IEnumerable<T>, Predicate<T>)

TypedAs<T>(ICollection)

Given a non-generic ICollection interface, wrap a generic ICollection<T> interface around it. The generic interface will enumerate the same objects as the underlying non-generic collection, but can be used in places that require a generic interface. The underlying non-generic collection must contain only items that are of type T or a type derived from it. This method is useful when interfacing older, non-generic collections to newer code that uses generic interfaces.

Declaration

public static ICollection<T> TypedAs<T>(ICollection untypedCollection)

Parameters

Type	Name	Description
System.Collections.ICollection	untypedCollection	An untyped collection. This collection should only contain items of type T or a type derived from it.

Returns

Type	Description
System.Collections.Generic.ICollection<T>	A generic ICollection<T> wrapper around untypedCollection. If untypedCollection is null, then null is returned.

Type Parameters

Name	Description
T	The item type of the wrapper collection.

Remarks

Some collections implement both generic and non-generic interfaces. For efficiency, this method will first attempt to cast untypedCollection to ICollection<T>. If that succeeds, it is returned; otherwise, a wrapper object is created.

Unlike the generic interface, the non-generic ICollection interfaces does not contain methods for adding or removing items from the collection. For this reason, the returned ICollection<T> will be read-only.

TypedAs<T>(IEnumerable)

Given a non-generic IEnumerable interface, wrap a generic IEnumerable<T> interface around it. The generic interface will enumerate the same objects as the underlying non-generic collection, but can be used in places that require a generic interface. The underlying non-generic collection must contain only items that are of type T or a type derived from it. This method is useful when interfacing older, non-generic collections to newer code that uses generic interfaces.

Declaration

public static IEnumerable<T> TypedAs<T>(IEnumerable untypedCollection)

Parameters

Type	Name	Description
System.Collections.IEnumerable	untypedCollection	An untyped collection. This collection should only contain items of type T or a type derived from it.

Returns

Type	Description
System.Collections.Generic.IEnumerable<T>	A generic IEnumerable<T> wrapper around untypedCollection. If untypedCollection is null, then null is returned.

Type Parameters

Name	Description
T	The item type of the wrapper collection.

Remarks

Some collections implement both generic and non-generic interfaces. For efficiency, this method will first attempt to cast untypedCollection to IEnumerable<T>. If that succeeds, it is returned; otherwise, a wrapper object is created.

TypedAs<T>(IList)

Given a non-generic IList interface, wrap a generic IList<T> interface around it. The generic interface will enumerate the same objects as the underlying non-generic list, but can be used in places that require a generic interface. The underlying non-generic list must contain only items that are of type T or a type derived from it. This method is useful when interfacing older, non-generic lists to newer code that uses generic interfaces.

Declaration

public static IList<T> TypedAs<T>(IList untypedList)

Parameters

Type	Name	Description
System.Collections.IList	untypedList	An untyped list. This list should only contain items of type T or a type derived from it.

Returns

Type	Description
System.Collections.Generic.IList<T>	A generic IList<T> wrapper around untypedlist. If untypedlist is null, then null is returned.

Type Parameters

Name	Description
T	The item type of the wrapper list.

Remarks

Some collections implement both generic and non-generic interfaces. For efficiency, this method will first attempt to cast untypedList to IList<T>. If that succeeds, it is returned; otherwise, a wrapper object is created.

Untyped<T>(ICollection<T>)

Given a generic ICollection<T> interface, wrap a non-generic (untyped) ICollection interface around it. The non-generic interface will contain the same objects as the underlying generic collection, but can be used in places that require a non-generic interface. This method is useful when interfacing generic interfaces with older code that uses non-generic interfaces.

Declaration

public static ICollection Untyped<T>(ICollection<T> typedCollection)

Parameters

Type	Name	Description
System.Collections.Generic.ICollection<T>	typedCollection	A typed collection to wrap.

Returns

Type	Description
System.Collections.ICollection	A non-generic ICollection wrapper around typedCollection. If typedCollection is null, then null is returned.

Type Parameters

Name	Description
T	The item type of the underlying collection.

Remarks

Many generic collections already implement the non-generic interfaces directly. This method will first attempt to simply cast typedCollection to ICollection. If that succeeds, it is returned; if it fails, then a wrapper object is created.

Untyped<T>(IList<T>)

Given a generic IList<T> interface, wrap a non-generic (untyped) IList interface around it. The non-generic interface will contain the same objects as the underlying generic list, but can be used in places that require a non-generic interface. This method is useful when interfacing generic interfaces with older code that uses non-generic interfaces.

Declaration

public static IList Untyped<T>(IList<T> typedList)

Parameters

Type	Name	Description
System.Collections.Generic.IList<T>	typedList	A typed list to wrap.

Returns

Type	Description
System.Collections.IList	A non-generic IList wrapper around typedList. If typedList is null, then null is returned.

Type Parameters

Name	Description
T	The item type of the underlying list.

Remarks

Many generic collections already implement the non-generic interfaces directly. This method will first attempt to simply cast typedList to IList. If that succeeds, it is returned; if it fails, then a wrapper object is created.