IDictionary<TKey, TValue> Interface

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Represents a generic collection of key/value pairs.

Namespace:  System.Collections.Generic
Assembly:  mscorlib (in mscorlib.dll)

Syntax

'Declaration
<DefaultMemberAttribute("Item")> _
Public Interface IDictionary(Of TKey, TValue) _
    Inherits ICollection(Of KeyValuePair(Of TKey, TValue)),  _
    IEnumerable(Of KeyValuePair(Of TKey, TValue)), IEnumerable

[DefaultMemberAttribute("Item")]
public interface IDictionary<TKey, TValue> : ICollection<KeyValuePair<TKey, TValue>>, 
    IEnumerable<KeyValuePair<TKey, TValue>>, IEnumerable

Type Parameters

• TKey
  The type of keys in the dictionary.

• TValue
  The type of values in the dictionary.

The IDictionary<TKey, TValue> type exposes the following members.

Properties

	Name	Description
	Count	Gets the number of elements contained in the ICollection<T>. (Inherited from ICollection<T>.)
	IsReadOnly	Gets a value indicating whether the ICollection<T> is read-only. (Inherited from ICollection<T>.)
	Item	Gets or sets the element with the specified key.
	Keys	Gets an ICollection<T> containing the keys of the IDictionary<TKey, TValue>.
	Values	Gets an ICollection<T> containing the values in the IDictionary<TKey, TValue>.

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Methods

	Name	Description
	Add(T)	Adds an item to the ICollection<T>. (Inherited from ICollection<T>.)
	Add(TKey, TValue)	Adds an element with the provided key and value to the IDictionary<TKey, TValue>.
	Clear	Removes all items from the ICollection<T>. (Inherited from ICollection<T>.)
	Contains	Determines whether the ICollection<T> contains a specific value. (Inherited from ICollection<T>.)
	ContainsKey	Determines whether the IDictionary<TKey, TValue> contains an element with the specified key.
	CopyTo	Copies the elements of the ICollection<T> to an Array, starting at a particular Array index. (Inherited from ICollection<T>.)
	GetEnumerator()	Returns an enumerator that iterates through a collection. (Inherited from IEnumerable.)
	GetEnumerator()	Returns an enumerator that iterates through the collection. (Inherited from IEnumerable<T>.)
	Remove(T)	Removes the first occurrence of a specific object from the ICollection<T>. (Inherited from ICollection<T>.)
	Remove(TKey)	Removes the element with the specified key from the IDictionary<TKey, TValue>.
	TryGetValue	Gets the value associated with the specified key.

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Extension Methods

	Name	Description
	Aggregate<KeyValuePair<TKey, TValue>>(Func<KeyValuePair<TKey, TValue>, KeyValuePair<TKey, TValue>, KeyValuePair<TKey, TValue>>)	Overloaded. Applies an accumulator function over a sequence. (Defined by Enumerable.)
	Aggregate<KeyValuePair<TKey, TValue>, TAccumulate>(TAccumulate, Func<TAccumulate, KeyValuePair<TKey, TValue>, TAccumulate>)	Overloaded. Applies an accumulator function over a sequence. The specified seed value is used as the initial accumulator value. (Defined by Enumerable.)
	Aggregate<KeyValuePair<TKey, TValue>, TAccumulate, TResult>(TAccumulate, Func<TAccumulate, KeyValuePair<TKey, TValue>, TAccumulate>, Func<TAccumulate, TResult>)	Overloaded. Applies an accumulator function over a sequence. The specified seed value is used as the initial accumulator value, and the specified function is used to select the result value. (Defined by Enumerable.)
	All<KeyValuePair<TKey, TValue>>	Determines whether all elements of a sequence satisfy a condition. (Defined by Enumerable.)
	Any<KeyValuePair<TKey, TValue>>()	Overloaded. Determines whether a sequence contains any elements. (Defined by Enumerable.)
	Any<KeyValuePair<TKey, TValue>>(Func<KeyValuePair<TKey, TValue>, Boolean>)	Overloaded. Determines whether any element of a sequence satisfies a condition. (Defined by Enumerable.)
	AsEnumerable<KeyValuePair<TKey, TValue>>	Returns the input typed as IEnumerable<T>. (Defined by Enumerable.)
	AsQueryable()	Overloaded. Converts an IEnumerable to an IQueryable. (Defined by Queryable.)
	AsQueryable<KeyValuePair<TKey, TValue>>()	Overloaded. Converts a generic IEnumerable<T> to a generic IQueryable<T>. (Defined by Queryable.)
	Average<KeyValuePair<TKey, TValue>>(Func<KeyValuePair<TKey, TValue>, Nullable<Decimal>>)	Overloaded. Computes the average of a sequence of nullable Decimal values that are obtained by invoking a transform function on each element of the input sequence. (Defined by Enumerable.)
	Average<KeyValuePair<TKey, TValue>>(Func<KeyValuePair<TKey, TValue>, Nullable<Double>>)	Overloaded. Computes the average of a sequence of nullable Double values that are obtained by invoking a transform function on each element of the input sequence. (Defined by Enumerable.)
	Average<KeyValuePair<TKey, TValue>>(Func<KeyValuePair<TKey, TValue>, Int32>)	Overloaded. Computes the average of a sequence of Int32 values that are obtained by invoking a transform function on each element of the input sequence. (Defined by Enumerable.)
	Average<KeyValuePair<TKey, TValue>>(Func<KeyValuePair<TKey, TValue>, Nullable<Int32>>)	Overloaded. Computes the average of a sequence of nullable Int32 values that are obtained by invoking a transform function on each element of the input sequence. (Defined by Enumerable.)
	Average<KeyValuePair<TKey, TValue>>(Func<KeyValuePair<TKey, TValue>, Int64>)	Overloaded. Computes the average of a sequence of Int64 values that are obtained by invoking a transform function on each element of the input sequence. (Defined by Enumerable.)
	Average<KeyValuePair<TKey, TValue>>(Func<KeyValuePair<TKey, TValue>, Nullable<Int64>>)	Overloaded. Computes the average of a sequence of nullable Int64 values that are obtained by invoking a transform function on each element of the input sequence. (Defined by Enumerable.)
	Average<KeyValuePair<TKey, TValue>>(Func<KeyValuePair<TKey, TValue>, Single>)	Overloaded. Computes the average of a sequence of Single values that are obtained by invoking a transform function on each element of the input sequence. (Defined by Enumerable.)
	Average<KeyValuePair<TKey, TValue>>(Func<KeyValuePair<TKey, TValue>, Nullable<Single>>)	Overloaded. Computes the average of a sequence of nullable Single values that are obtained by invoking a transform function on each element of the input sequence. (Defined by Enumerable.)
	Average<KeyValuePair<TKey, TValue>>(Func<KeyValuePair<TKey, TValue>, Double>)	Overloaded. Computes the average of a sequence of Double values that are obtained by invoking a transform function on each element of the input sequence. (Defined by Enumerable.)
	Average<KeyValuePair<TKey, TValue>>(Func<KeyValuePair<TKey, TValue>, Decimal>)	Overloaded. Computes the average of a sequence of Decimal values that are obtained by invoking a transform function on each element of the input sequence. (Defined by Enumerable.)
	Cast<TResult>	Converts the elements of an IEnumerable to the specified type. (Defined by Enumerable.)
	Concat<KeyValuePair<TKey, TValue>>	Concatenates two sequences. (Defined by Enumerable.)
	Contains<KeyValuePair<TKey, TValue>>(KeyValuePair<TKey, TValue>)	Overloaded. Determines whether a sequence contains a specified element by using the default equality comparer. (Defined by Enumerable.)
	Contains<KeyValuePair<TKey, TValue>>(KeyValuePair<TKey, TValue>, IEqualityComparer<KeyValuePair<TKey, TValue>>)	Overloaded. Determines whether a sequence contains a specified element by using a specified IEqualityComparer<T>. (Defined by Enumerable.)
	Count<KeyValuePair<TKey, TValue>>()	Overloaded. Returns the number of elements in a sequence. (Defined by Enumerable.)
	Count<KeyValuePair<TKey, TValue>>(Func<KeyValuePair<TKey, TValue>, Boolean>)	Overloaded. Returns a number that represents how many elements in the specified sequence satisfy a condition. (Defined by Enumerable.)
	DefaultIfEmpty<KeyValuePair<TKey, TValue>>()	Overloaded. Returns the elements of the specified sequence or the type parameter's default value in a singleton collection if the sequence is empty. (Defined by Enumerable.)
	DefaultIfEmpty<KeyValuePair<TKey, TValue>>(KeyValuePair<TKey, TValue>)	Overloaded. Returns the elements of the specified sequence or the specified value in a singleton collection if the sequence is empty. (Defined by Enumerable.)
	Distinct<KeyValuePair<TKey, TValue>>()	Overloaded. Returns distinct elements from a sequence by using the default equality comparer to compare values. (Defined by Enumerable.)
	Distinct<KeyValuePair<TKey, TValue>>(IEqualityComparer<KeyValuePair<TKey, TValue>>)	Overloaded. Returns distinct elements from a sequence by using a specified IEqualityComparer<T> to compare values. (Defined by Enumerable.)
	ElementAt<KeyValuePair<TKey, TValue>>	Returns the element at a specified index in a sequence. (Defined by Enumerable.)
	ElementAtOrDefault<KeyValuePair<TKey, TValue>>	Returns the element at a specified index in a sequence or a default value if the index is out of range. (Defined by Enumerable.)
	Except<KeyValuePair<TKey, TValue>>(IEnumerable<KeyValuePair<TKey, TValue>>)	Overloaded. Produces the set difference of two sequences by using the default equality comparer to compare values. (Defined by Enumerable.)
	Except<KeyValuePair<TKey, TValue>>(IEnumerable<KeyValuePair<TKey, TValue>>, IEqualityComparer<KeyValuePair<TKey, TValue>>)	Overloaded. Produces the set difference of two sequences by using the specified IEqualityComparer<T> to compare values. (Defined by Enumerable.)
	First<KeyValuePair<TKey, TValue>>()	Overloaded. Returns the first element of a sequence. (Defined by Enumerable.)
	First<KeyValuePair<TKey, TValue>>(Func<KeyValuePair<TKey, TValue>, Boolean>)	Overloaded. Returns the first element in a sequence that satisfies a specified condition. (Defined by Enumerable.)
	FirstOrDefault<KeyValuePair<TKey, TValue>>()	Overloaded. Returns the first element of a sequence, or a default value if the sequence contains no elements. (Defined by Enumerable.)
	FirstOrDefault<KeyValuePair<TKey, TValue>>(Func<KeyValuePair<TKey, TValue>, Boolean>)	Overloaded. Returns the first element of the sequence that satisfies a condition or a default value if no such element is found. (Defined by Enumerable.)
	GroupBy<KeyValuePair<TKey, TValue>, TKey>(Func<KeyValuePair<TKey, TValue>, TKey>)	Overloaded. Groups the elements of a sequence according to a specified key selector function. (Defined by Enumerable.)
	GroupBy<KeyValuePair<TKey, TValue>, TKey>(Func<KeyValuePair<TKey, TValue>, TKey>, IEqualityComparer<TKey>)	Overloaded. Groups the elements of a sequence according to a specified key selector function and compares the keys by using a specified comparer. (Defined by Enumerable.)
	GroupBy<KeyValuePair<TKey, TValue>, TKey, TElement>(Func<KeyValuePair<TKey, TValue>, TKey>, Func<KeyValuePair<TKey, TValue>, TElement>)	Overloaded. Groups the elements of a sequence according to a specified key selector function and projects the elements for each group by using a specified function. (Defined by Enumerable.)
	GroupBy<KeyValuePair<TKey, TValue>, TKey, TResult>(Func<KeyValuePair<TKey, TValue>, TKey>, Func<TKey, IEnumerable<KeyValuePair<TKey, TValue>>, TResult>)	Overloaded. Groups the elements of a sequence according to a specified key selector function and creates a result value from each group and its key. (Defined by Enumerable.)
	GroupBy<KeyValuePair<TKey, TValue>, TKey, TElement>(Func<KeyValuePair<TKey, TValue>, TKey>, Func<KeyValuePair<TKey, TValue>, TElement>, IEqualityComparer<TKey>)	Overloaded. Groups the elements of a sequence according to a key selector function. The keys are compared by using a comparer and each group's elements are projected by using a specified function. (Defined by Enumerable.)
	GroupBy<KeyValuePair<TKey, TValue>, TKey, TResult>(Func<KeyValuePair<TKey, TValue>, TKey>, Func<TKey, IEnumerable<KeyValuePair<TKey, TValue>>, TResult>, IEqualityComparer<TKey>)	Overloaded. Groups the elements of a sequence according to a specified key selector function and creates a result value from each group and its key. The keys are compared by using a specified comparer. (Defined by Enumerable.)
	GroupBy<KeyValuePair<TKey, TValue>, TKey, TElement, TResult>(Func<KeyValuePair<TKey, TValue>, TKey>, Func<KeyValuePair<TKey, TValue>, TElement>, Func<TKey, IEnumerable<TElement>, TResult>)	Overloaded. Groups the elements of a sequence according to a specified key selector function and creates a result value from each group and its key. The elements of each group are projected by using a specified function. (Defined by Enumerable.)
	GroupBy<KeyValuePair<TKey, TValue>, TKey, TElement, TResult>(Func<KeyValuePair<TKey, TValue>, TKey>, Func<KeyValuePair<TKey, TValue>, TElement>, Func<TKey, IEnumerable<TElement>, TResult>, IEqualityComparer<TKey>)	Overloaded. Groups the elements of a sequence according to a specified key selector function and creates a result value from each group and its key. Key values are compared by using a specified comparer, and the elements of each group are projected by using a specified function. (Defined by Enumerable.)
	GroupJoin<KeyValuePair<TKey, TValue>, TInner, TKey, TResult>(IEnumerable<TInner>, Func<KeyValuePair<TKey, TValue>, TKey>, Func<TInner, TKey>, Func<KeyValuePair<TKey, TValue>, IEnumerable<TInner>, TResult>)	Overloaded. Correlates the elements of two sequences based on equality of keys and groups the results. The default equality comparer is used to compare keys. (Defined by Enumerable.)
	GroupJoin<KeyValuePair<TKey, TValue>, TInner, TKey, TResult>(IEnumerable<TInner>, Func<KeyValuePair<TKey, TValue>, TKey>, Func<TInner, TKey>, Func<KeyValuePair<TKey, TValue>, IEnumerable<TInner>, TResult>, IEqualityComparer<TKey>)	Overloaded. Correlates the elements of two sequences based on key equality and groups the results. A specified IEqualityComparer<T> is used to compare keys. (Defined by Enumerable.)
	Intersect<KeyValuePair<TKey, TValue>>(IEnumerable<KeyValuePair<TKey, TValue>>)	Overloaded. Produces the set intersection of two sequences by using the default equality comparer to compare values. (Defined by Enumerable.)
	Intersect<KeyValuePair<TKey, TValue>>(IEnumerable<KeyValuePair<TKey, TValue>>, IEqualityComparer<KeyValuePair<TKey, TValue>>)	Overloaded. Produces the set intersection of two sequences by using the specified IEqualityComparer<T> to compare values. (Defined by Enumerable.)
	Join<KeyValuePair<TKey, TValue>, TInner, TKey, TResult>(IEnumerable<TInner>, Func<KeyValuePair<TKey, TValue>, TKey>, Func<TInner, TKey>, Func<KeyValuePair<TKey, TValue>, TInner, TResult>)	Overloaded. Correlates the elements of two sequences based on matching keys. The default equality comparer is used to compare keys. (Defined by Enumerable.)
	Join<KeyValuePair<TKey, TValue>, TInner, TKey, TResult>(IEnumerable<TInner>, Func<KeyValuePair<TKey, TValue>, TKey>, Func<TInner, TKey>, Func<KeyValuePair<TKey, TValue>, TInner, TResult>, IEqualityComparer<TKey>)	Overloaded. Correlates the elements of two sequences based on matching keys. A specified IEqualityComparer<T> is used to compare keys. (Defined by Enumerable.)
	Last<KeyValuePair<TKey, TValue>>()	Overloaded. Returns the last element of a sequence. (Defined by Enumerable.)
	Last<KeyValuePair<TKey, TValue>>(Func<KeyValuePair<TKey, TValue>, Boolean>)	Overloaded. Returns the last element of a sequence that satisfies a specified condition. (Defined by Enumerable.)
	LastOrDefault<KeyValuePair<TKey, TValue>>()	Overloaded. Returns the last element of a sequence, or a default value if the sequence contains no elements. (Defined by Enumerable.)
	LastOrDefault<KeyValuePair<TKey, TValue>>(Func<KeyValuePair<TKey, TValue>, Boolean>)	Overloaded. Returns the last element of a sequence that satisfies a condition or a default value if no such element is found. (Defined by Enumerable.)
	LongCount<KeyValuePair<TKey, TValue>>()	Overloaded. Returns an Int64 that represents the total number of elements in a sequence. (Defined by Enumerable.)
	LongCount<KeyValuePair<TKey, TValue>>(Func<KeyValuePair<TKey, TValue>, Boolean>)	Overloaded. Returns an Int64 that represents how many elements in a sequence satisfy a condition. (Defined by Enumerable.)
	Max<KeyValuePair<TKey, TValue>>()	Overloaded. Returns the maximum value in a generic sequence. (Defined by Enumerable.)
	Max<KeyValuePair<TKey, TValue>>(Func<KeyValuePair<TKey, TValue>, Nullable<Decimal>>)	Overloaded. Invokes a transform function on each element of a sequence and returns the maximum nullable Decimal value. (Defined by Enumerable.)
	Max<KeyValuePair<TKey, TValue>>(Func<KeyValuePair<TKey, TValue>, Nullable<Double>>)	Overloaded. Invokes a transform function on each element of a sequence and returns the maximum nullable Double value. (Defined by Enumerable.)
	Max<KeyValuePair<TKey, TValue>>(Func<KeyValuePair<TKey, TValue>, Int32>)	Overloaded. Invokes a transform function on each element of a sequence and returns the maximum Int32 value. (Defined by Enumerable.)
	Max<KeyValuePair<TKey, TValue>>(Func<KeyValuePair<TKey, TValue>, Nullable<Int32>>)	Overloaded. Invokes a transform function on each element of a sequence and returns the maximum nullable Int32 value. (Defined by Enumerable.)
	Max<KeyValuePair<TKey, TValue>>(Func<KeyValuePair<TKey, TValue>, Int64>)	Overloaded. Invokes a transform function on each element of a sequence and returns the maximum Int64 value. (Defined by Enumerable.)
	Max<KeyValuePair<TKey, TValue>>(Func<KeyValuePair<TKey, TValue>, Nullable<Int64>>)	Overloaded. Invokes a transform function on each element of a sequence and returns the maximum nullable Int64 value. (Defined by Enumerable.)
	Max<KeyValuePair<TKey, TValue>>(Func<KeyValuePair<TKey, TValue>, Single>)	Overloaded. Invokes a transform function on each element of a sequence and returns the maximum Single value. (Defined by Enumerable.)
	Max<KeyValuePair<TKey, TValue>>(Func<KeyValuePair<TKey, TValue>, Nullable<Single>>)	Overloaded. Invokes a transform function on each element of a sequence and returns the maximum nullable Single value. (Defined by Enumerable.)
	Max<KeyValuePair<TKey, TValue>>(Func<KeyValuePair<TKey, TValue>, Double>)	Overloaded. Invokes a transform function on each element of a sequence and returns the maximum Double value. (Defined by Enumerable.)
	Max<KeyValuePair<TKey, TValue>>(Func<KeyValuePair<TKey, TValue>, Decimal>)	Overloaded. Invokes a transform function on each element of a sequence and returns the maximum Decimal value. (Defined by Enumerable.)
	Max<KeyValuePair<TKey, TValue>, TResult>(Func<KeyValuePair<TKey, TValue>, TResult>)	Overloaded. Invokes a transform function on each element of a generic sequence and returns the maximum resulting value. (Defined by Enumerable.)
	Min<KeyValuePair<TKey, TValue>>()	Overloaded. Returns the minimum value in a generic sequence. (Defined by Enumerable.)
	Min<KeyValuePair<TKey, TValue>>(Func<KeyValuePair<TKey, TValue>, Nullable<Decimal>>)	Overloaded. Invokes a transform function on each element of a sequence and returns the minimum nullable Decimal value. (Defined by Enumerable.)
	Min<KeyValuePair<TKey, TValue>>(Func<KeyValuePair<TKey, TValue>, Nullable<Double>>)	Overloaded. Invokes a transform function on each element of a sequence and returns the minimum nullable Double value. (Defined by Enumerable.)
	Min<KeyValuePair<TKey, TValue>>(Func<KeyValuePair<TKey, TValue>, Int32>)	Overloaded. Invokes a transform function on each element of a sequence and returns the minimum Int32 value. (Defined by Enumerable.)
	Min<KeyValuePair<TKey, TValue>>(Func<KeyValuePair<TKey, TValue>, Nullable<Int32>>)	Overloaded. Invokes a transform function on each element of a sequence and returns the minimum nullable Int32 value. (Defined by Enumerable.)
	Min<KeyValuePair<TKey, TValue>>(Func<KeyValuePair<TKey, TValue>, Int64>)	Overloaded. Invokes a transform function on each element of a sequence and returns the minimum Int64 value. (Defined by Enumerable.)
	Min<KeyValuePair<TKey, TValue>>(Func<KeyValuePair<TKey, TValue>, Nullable<Int64>>)	Overloaded. Invokes a transform function on each element of a sequence and returns the minimum nullable Int64 value. (Defined by Enumerable.)
	Min<KeyValuePair<TKey, TValue>>(Func<KeyValuePair<TKey, TValue>, Single>)	Overloaded. Invokes a transform function on each element of a sequence and returns the minimum Single value. (Defined by Enumerable.)
	Min<KeyValuePair<TKey, TValue>>(Func<KeyValuePair<TKey, TValue>, Nullable<Single>>)	Overloaded. Invokes a transform function on each element of a sequence and returns the minimum nullable Single value. (Defined by Enumerable.)
	Min<KeyValuePair<TKey, TValue>>(Func<KeyValuePair<TKey, TValue>, Double>)	Overloaded. Invokes a transform function on each element of a sequence and returns the minimum Double value. (Defined by Enumerable.)
	Min<KeyValuePair<TKey, TValue>>(Func<KeyValuePair<TKey, TValue>, Decimal>)	Overloaded. Invokes a transform function on each element of a sequence and returns the minimum Decimal value. (Defined by Enumerable.)
	Min<KeyValuePair<TKey, TValue>, TResult>(Func<KeyValuePair<TKey, TValue>, TResult>)	Overloaded. Invokes a transform function on each element of a generic sequence and returns the minimum resulting value. (Defined by Enumerable.)
	OfType<TResult>	Filters the elements of an IEnumerable based on a specified type. (Defined by Enumerable.)
	OrderBy<KeyValuePair<TKey, TValue>, TKey>(Func<KeyValuePair<TKey, TValue>, TKey>)	Overloaded. Sorts the elements of a sequence in ascending order according to a key. (Defined by Enumerable.)
	OrderBy<KeyValuePair<TKey, TValue>, TKey>(Func<KeyValuePair<TKey, TValue>, TKey>, IComparer<TKey>)	Overloaded. Sorts the elements of a sequence in ascending order by using a specified comparer. (Defined by Enumerable.)
	OrderByDescending<KeyValuePair<TKey, TValue>, TKey>(Func<KeyValuePair<TKey, TValue>, TKey>)	Overloaded. Sorts the elements of a sequence in descending order according to a key. (Defined by Enumerable.)
	OrderByDescending<KeyValuePair<TKey, TValue>, TKey>(Func<KeyValuePair<TKey, TValue>, TKey>, IComparer<TKey>)	Overloaded. Sorts the elements of a sequence in descending order by using a specified comparer. (Defined by Enumerable.)
	Reverse<KeyValuePair<TKey, TValue>>	Inverts the order of the elements in a sequence. (Defined by Enumerable.)
	Select<KeyValuePair<TKey, TValue>, TResult>(Func<KeyValuePair<TKey, TValue>, TResult>)	Overloaded. Projects each element of a sequence into a new form. (Defined by Enumerable.)
	Select<KeyValuePair<TKey, TValue>, TResult>(Func<KeyValuePair<TKey, TValue>, Int32, TResult>)	Overloaded. Projects each element of a sequence into a new form by incorporating the element's index. (Defined by Enumerable.)
	SelectMany<KeyValuePair<TKey, TValue>, TResult>(Func<KeyValuePair<TKey, TValue>, IEnumerable<TResult>>)	Overloaded. Projects each element of a sequence to an IEnumerable<T> and flattens the resulting sequences into one sequence. (Defined by Enumerable.)
	SelectMany<KeyValuePair<TKey, TValue>, TResult>(Func<KeyValuePair<TKey, TValue>, Int32, IEnumerable<TResult>>)	Overloaded. Projects each element of a sequence to an IEnumerable<T>, and flattens the resulting sequences into one sequence. The index of each source element is used in the projected form of that element. (Defined by Enumerable.)
	SelectMany<KeyValuePair<TKey, TValue>, TCollection, TResult>(Func<KeyValuePair<TKey, TValue>, Int32, IEnumerable<TCollection>>, Func<KeyValuePair<TKey, TValue>, TCollection, TResult>)	Overloaded. Projects each element of a sequence to an IEnumerable<T>, flattens the resulting sequences into one sequence, and invokes a result selector function on each element therein. The index of each source element is used in the intermediate projected form of that element. (Defined by Enumerable.)
	SelectMany<KeyValuePair<TKey, TValue>, TCollection, TResult>(Func<KeyValuePair<TKey, TValue>, IEnumerable<TCollection>>, Func<KeyValuePair<TKey, TValue>, TCollection, TResult>)	Overloaded. Projects each element of a sequence to an IEnumerable<T>, flattens the resulting sequences into one sequence, and invokes a result selector function on each element therein. (Defined by Enumerable.)
	SequenceEqual<KeyValuePair<TKey, TValue>>(IEnumerable<KeyValuePair<TKey, TValue>>)	Overloaded. Determines whether two sequences are equal by comparing the elements by using the default equality comparer for their type. (Defined by Enumerable.)
	SequenceEqual<KeyValuePair<TKey, TValue>>(IEnumerable<KeyValuePair<TKey, TValue>>, IEqualityComparer<KeyValuePair<TKey, TValue>>)	Overloaded. Determines whether two sequences are equal by comparing their elements by using a specified IEqualityComparer<T>. (Defined by Enumerable.)
	Single<KeyValuePair<TKey, TValue>>()	Overloaded. Returns the only element of a sequence, and throws an exception if there is not exactly one element in the sequence. (Defined by Enumerable.)
	Single<KeyValuePair<TKey, TValue>>(Func<KeyValuePair<TKey, TValue>, Boolean>)	Overloaded. Returns the only element of a sequence that satisfies a specified condition, and throws an exception if more than one such element exists. (Defined by Enumerable.)
	SingleOrDefault<KeyValuePair<TKey, TValue>>()	Overloaded. Returns the only element of a sequence, or a default value if the sequence is empty; this method throws an exception if there is more than one element in the sequence. (Defined by Enumerable.)
	SingleOrDefault<KeyValuePair<TKey, TValue>>(Func<KeyValuePair<TKey, TValue>, Boolean>)	Overloaded. Returns the only element of a sequence that satisfies a specified condition or a default value if no such element exists; this method throws an exception if more than one element satisfies the condition. (Defined by Enumerable.)
	Skip<KeyValuePair<TKey, TValue>>	Bypasses a specified number of elements in a sequence and then returns the remaining elements. (Defined by Enumerable.)
	SkipWhile<KeyValuePair<TKey, TValue>>(Func<KeyValuePair<TKey, TValue>, Boolean>)	Overloaded. Bypasses elements in a sequence as long as a specified condition is true and then returns the remaining elements. (Defined by Enumerable.)
	SkipWhile<KeyValuePair<TKey, TValue>>(Func<KeyValuePair<TKey, TValue>, Int32, Boolean>)	Overloaded. Bypasses elements in a sequence as long as a specified condition is true and then returns the remaining elements. The element's index is used in the logic of the predicate function. (Defined by Enumerable.)
	Sum<KeyValuePair<TKey, TValue>>(Func<KeyValuePair<TKey, TValue>, Nullable<Decimal>>)	Overloaded. Computes the sum of the sequence of nullable Decimal values that are obtained by invoking a transform function on each element of the input sequence. (Defined by Enumerable.)
	Sum<KeyValuePair<TKey, TValue>>(Func<KeyValuePair<TKey, TValue>, Nullable<Double>>)	Overloaded. Computes the sum of the sequence of nullable Double values that are obtained by invoking a transform function on each element of the input sequence. (Defined by Enumerable.)
	Sum<KeyValuePair<TKey, TValue>>(Func<KeyValuePair<TKey, TValue>, Int32>)	Overloaded. Computes the sum of the sequence of Int32 values that are obtained by invoking a transform function on each element of the input sequence. (Defined by Enumerable.)
	Sum<KeyValuePair<TKey, TValue>>(Func<KeyValuePair<TKey, TValue>, Nullable<Int32>>)	Overloaded. Computes the sum of the sequence of nullable Int32 values that are obtained by invoking a transform function on each element of the input sequence. (Defined by Enumerable.)
	Sum<KeyValuePair<TKey, TValue>>(Func<KeyValuePair<TKey, TValue>, Int64>)	Overloaded. Computes the sum of the sequence of Int64 values that are obtained by invoking a transform function on each element of the input sequence. (Defined by Enumerable.)
	Sum<KeyValuePair<TKey, TValue>>(Func<KeyValuePair<TKey, TValue>, Nullable<Int64>>)	Overloaded. Computes the sum of the sequence of nullable Int64 values that are obtained by invoking a transform function on each element of the input sequence. (Defined by Enumerable.)
	Sum<KeyValuePair<TKey, TValue>>(Func<KeyValuePair<TKey, TValue>, Single>)	Overloaded. Computes the sum of the sequence of Single values that are obtained by invoking a transform function on each element of the input sequence. (Defined by Enumerable.)
	Sum<KeyValuePair<TKey, TValue>>(Func<KeyValuePair<TKey, TValue>, Nullable<Single>>)	Overloaded. Computes the sum of the sequence of nullable Single values that are obtained by invoking a transform function on each element of the input sequence. (Defined by Enumerable.)
	Sum<KeyValuePair<TKey, TValue>>(Func<KeyValuePair<TKey, TValue>, Double>)	Overloaded. Computes the sum of the sequence of Double values that are obtained by invoking a transform function on each element of the input sequence. (Defined by Enumerable.)
	Sum<KeyValuePair<TKey, TValue>>(Func<KeyValuePair<TKey, TValue>, Decimal>)	Overloaded. Computes the sum of the sequence of Decimal values that are obtained by invoking a transform function on each element of the input sequence. (Defined by Enumerable.)
	Take<KeyValuePair<TKey, TValue>>	Returns a specified number of contiguous elements from the start of a sequence. (Defined by Enumerable.)
	TakeWhile<KeyValuePair<TKey, TValue>>(Func<KeyValuePair<TKey, TValue>, Boolean>)	Overloaded. Returns elements from a sequence as long as a specified condition is true. (Defined by Enumerable.)
	TakeWhile<KeyValuePair<TKey, TValue>>(Func<KeyValuePair<TKey, TValue>, Int32, Boolean>)	Overloaded. Returns elements from a sequence as long as a specified condition is true. The element's index is used in the logic of the predicate function. (Defined by Enumerable.)
	ToArray<KeyValuePair<TKey, TValue>>	Creates an array from a IEnumerable<T>. (Defined by Enumerable.)
	ToDictionary<KeyValuePair<TKey, TValue>, TKey>(Func<KeyValuePair<TKey, TValue>, TKey>)	Overloaded. Creates a Dictionary<TKey, TValue> from an IEnumerable<T> according to a specified key selector function. (Defined by Enumerable.)
	ToDictionary<KeyValuePair<TKey, TValue>, TKey>(Func<KeyValuePair<TKey, TValue>, TKey>, IEqualityComparer<TKey>)	Overloaded. Creates a Dictionary<TKey, TValue> from an IEnumerable<T> according to a specified key selector function and key comparer. (Defined by Enumerable.)
	ToDictionary<KeyValuePair<TKey, TValue>, TKey, TElement>(Func<KeyValuePair<TKey, TValue>, TKey>, Func<KeyValuePair<TKey, TValue>, TElement>)	Overloaded. Creates a Dictionary<TKey, TValue> from an IEnumerable<T> according to specified key selector and element selector functions. (Defined by Enumerable.)
	ToDictionary<KeyValuePair<TKey, TValue>, TKey, TElement>(Func<KeyValuePair<TKey, TValue>, TKey>, Func<KeyValuePair<TKey, TValue>, TElement>, IEqualityComparer<TKey>)	Overloaded. Creates a Dictionary<TKey, TValue> from an IEnumerable<T> according to a specified key selector function, a comparer, and an element selector function. (Defined by Enumerable.)
	ToList<KeyValuePair<TKey, TValue>>	Creates a List<T> from an IEnumerable<T>. (Defined by Enumerable.)
	ToLookup<KeyValuePair<TKey, TValue>, TKey>(Func<KeyValuePair<TKey, TValue>, TKey>)	Overloaded. Creates a Lookup<TKey, TElement> from an IEnumerable<T> according to a specified key selector function. (Defined by Enumerable.)
	ToLookup<KeyValuePair<TKey, TValue>, TKey>(Func<KeyValuePair<TKey, TValue>, TKey>, IEqualityComparer<TKey>)	Overloaded. Creates a Lookup<TKey, TElement> from an IEnumerable<T> according to a specified key selector function and key comparer. (Defined by Enumerable.)
	ToLookup<KeyValuePair<TKey, TValue>, TKey, TElement>(Func<KeyValuePair<TKey, TValue>, TKey>, Func<KeyValuePair<TKey, TValue>, TElement>)	Overloaded. Creates a Lookup<TKey, TElement> from an IEnumerable<T> according to specified key selector and element selector functions. (Defined by Enumerable.)
	ToLookup<KeyValuePair<TKey, TValue>, TKey, TElement>(Func<KeyValuePair<TKey, TValue>, TKey>, Func<KeyValuePair<TKey, TValue>, TElement>, IEqualityComparer<TKey>)	Overloaded. Creates a Lookup<TKey, TElement> from an IEnumerable<T> according to a specified key selector function, a comparer and an element selector function. (Defined by Enumerable.)
	Union<KeyValuePair<TKey, TValue>>(IEnumerable<KeyValuePair<TKey, TValue>>)	Overloaded. Produces the set union of two sequences by using the default equality comparer. (Defined by Enumerable.)
	Union<KeyValuePair<TKey, TValue>>(IEnumerable<KeyValuePair<TKey, TValue>>, IEqualityComparer<KeyValuePair<TKey, TValue>>)	Overloaded. Produces the set union of two sequences by using a specified IEqualityComparer<T>. (Defined by Enumerable.)
	Where<KeyValuePair<TKey, TValue>>(Func<KeyValuePair<TKey, TValue>, Boolean>)	Overloaded. Filters a sequence of values based on a predicate. (Defined by Enumerable.)
	Where<KeyValuePair<TKey, TValue>>(Func<KeyValuePair<TKey, TValue>, Int32, Boolean>)	Overloaded. Filters a sequence of values based on a predicate. Each element's index is used in the logic of the predicate function. (Defined by Enumerable.)
	Zip<KeyValuePair<TKey, TValue>, TSecond, TResult>	Merges two sequences by using the specified predicate function. (Defined by Enumerable.)

Top

Remarks

The IDictionary<TKey, TValue> interface is the base interface for generic collections of key/value pairs.

Each element is a key/value pair stored in a KeyValuePair<TKey, TValue> object.

Each pair must have a unique key. Implementations can vary in whether they allow key to be nulla null reference (Nothing in Visual Basic). The value can be nulla null reference (Nothing in Visual Basic) and does not have to be unique. The IDictionary<TKey, TValue> interface allows the contained keys and values to be enumerated, but it does not imply any particular sort order.

The foreach statement of the C# language (For Each in Visual Basic, for each in C++) requires the type of each element in the collection. Since each element of the IDictionary<TKey, TValue> is a key/value pair, the element type is not the type of the key or the type of the value. Instead, the element type is KeyValuePair<TKey, TValue>. For example:

foreach (KeyValuePair<int, string> kvp in myDictionary) {...}

for each (KeyValuePair<int, String^> kvp in myDictionary) {...}

For Each kvp As KeyValuePair(Of Integer, String) In myDictionary
    ...
Next kvp

The foreach statement is a wrapper around the enumerator, which only allows reading from, not writing to, the collection.

Note:
Because keys can be inherited and their behavior changed, their absolute uniqueness cannot be guaranteed by making comparisons using the Equals method.

Notes to Implementers

The implementing class must have a means to compare keys.

Examples

The following code example creates an empty Dictionary<TKey, TValue> of strings, with integer keys, and accesses it through the IDictionary<TKey, TValue> interface.

The code example uses the Add method to add some elements. The example demonstrates that the Add method throws ArgumentException when attempting to add a duplicate key.

The example uses the Item property (the indexer in C#) to retrieve values, demonstrating that a KeyNotFoundException is thrown when a requested key is not present, and showing that the value associated with a key can be replaced.

The example shows how to use the TryGetValue method as a more efficient way to retrieve values if a program often must try key values that are not in the dictionary, and how to use the ContainsKey method to test whether a key exists prior to calling the Add method.

Finally, the example shows how to enumerate the keys and values in the dictionary, and how to enumerate the values alone using the Values property.

Imports System.Collections.Generic

Public Class Example

   Public Shared Sub Demo(ByVal outputBlock As System.Windows.Controls.TextBlock)

      ' Create a new dictionary of strings, with string keys, 
      ' and access it through the IDictionary generic interface.
      Dim openWith As IDictionary(Of String, String) = _
          New Dictionary(Of String, String)

      ' Add some elements to the dictionary. There are no 
      ' duplicate keys, but some of the values are duplicates.
      openWith.Add("txt", "notepad.exe")
      openWith.Add("bmp", "paint.exe")
      openWith.Add("dib", "paint.exe")
      openWith.Add("rtf", "wordpad.exe")

      ' The Add method throws an exception if the new key is 
      ' already in the dictionary.
      Try
         openWith.Add("txt", "winword.exe")
      Catch
         outputBlock.Text &= "An element with Key = ""txt"" already exists." & vbCrLf
      End Try

      ' The Item property is the default property, so you 
      ' can omit its name when accessing elements. 
      outputBlock.Text &= String.Format("For key = ""rtf"", value = {0}.", _
          openWith("rtf")) & vbCrLf

      ' The default Item property can be used to change the value
      ' associated with a key.
      openWith("rtf") = "winword.exe"
      outputBlock.Text &= String.Format("For key = ""rtf"", value = {0}.", _
          openWith("rtf")) & vbCrLf

      ' If a key does not exist, setting the default item property
      ' for that key adds a new key/value pair.
      openWith("doc") = "winword.exe"

      ' The default Item property throws an exception if the requested
      ' key is not in the dictionary.
      Try
         outputBlock.Text &= String.Format("For key = ""tif"", value = {0}.", _
             openWith("tif")) & vbCrLf
      Catch
         outputBlock.Text &= "Key = ""tif"" is not found." & vbCrLf
      End Try

      ' When a program often has to try keys that turn out not to
      ' be in the dictionary, TryGetValue can be a more efficient 
      ' way to retrieve values.
      Dim value As String = ""
      If openWith.TryGetValue("tif", value) Then
         outputBlock.Text &= String.Format("For key = ""tif"", value = {0}.", value) & vbCrLf
      Else
         outputBlock.Text &= "Key = ""tif"" is not found." & vbCrLf
      End If

      ' ContainsKey can be used to test keys before inserting 
      ' them.
      If Not openWith.ContainsKey("ht") Then
         openWith.Add("ht", "hypertrm.exe")
         outputBlock.Text &= String.Format("Value added for key = ""ht"": {0}", _
             openWith("ht")) & vbCrLf
      End If

      ' When you use foreach to enumerate dictionary elements,
      ' the elements are retrieved as KeyValuePair objects.
      outputBlock.Text &= vbCrLf
      For Each kvp As KeyValuePair(Of String, String) In openWith
         outputBlock.Text &= String.Format("Key = {0}, Value = {1}", _
             kvp.Key, kvp.Value) & vbCrLf
      Next kvp

      ' To get the values alone, use the Values property.
      Dim icoll As ICollection(Of String) = openWith.Values

      ' The elements of the ValueCollection are strongly typed
      ' with the type that was specified for dictionary values.
      outputBlock.Text &= vbCrLf
      For Each s As String In icoll
         outputBlock.Text &= String.Format("Value = {0}", s) & vbCrLf
      Next s

      ' To get the keys alone, use the Keys property.
      icoll = openWith.Keys

      ' The elements of the ValueCollection are strongly typed
      ' with the type that was specified for dictionary values.
      outputBlock.Text &= vbCrLf
      For Each s As String In icoll
         outputBlock.Text &= String.Format("Key = {0}", s) & vbCrLf
      Next s

      ' Use the Remove method to remove a key/value pair.
      outputBlock.Text &= vbLf + "Remove(""doc"")" & vbCrLf
      openWith.Remove("doc")

      If Not openWith.ContainsKey("doc") Then
         outputBlock.Text &= "Key ""doc"" is not found." & vbCrLf
      End If

   End Sub

End Class

' This code example produces the following output:
'
'An element with Key = "txt" already exists.
'For key = "rtf", value = wordpad.exe.
'For key = "rtf", value = winword.exe.
'Key = "tif" is not found.
'Key = "tif" is not found.
'Value added for key = "ht": hypertrm.exe
'
'Key = txt, Value = notepad.exe
'Key = bmp, Value = paint.exe
'Key = dib, Value = paint.exe
'Key = rtf, Value = winword.exe
'Key = doc, Value = winword.exe
'Key = ht, Value = hypertrm.exe
'
'Value = notepad.exe
'Value = paint.exe
'Value = paint.exe
'Value = winword.exe
'Value = winword.exe
'Value = hypertrm.exe
'
'Key = txt
'Key = bmp
'Key = dib
'Key = rtf
'Key = doc
'Key = ht
'
'Remove("doc")
'Key "doc" is not found.
' 

using System;
using System.Collections.Generic;

public class Example
{
   public static void Demo(System.Windows.Controls.TextBlock outputBlock)
   {
      // Create a new dictionary of strings, with string keys, 
      // and access it through the IDictionary generic interface.
      IDictionary<string, string> openWith =
          new Dictionary<string, string>();

      // Add some elements to the dictionary. There are no 
      // duplicate keys, but some of the values are duplicates.
      openWith.Add("txt", "notepad.exe");
      openWith.Add("bmp", "paint.exe");
      openWith.Add("dib", "paint.exe");
      openWith.Add("rtf", "wordpad.exe");

      // The Add method throws an exception if the new key is 
      // already in the dictionary.
      try
      {
         openWith.Add("txt", "winword.exe");
      }
      catch (ArgumentException)
      {
         outputBlock.Text += "An element with Key = \"txt\" already exists." + "\n";
      }

      // The Item property is another name for the indexer, so you 
      // can omit its name when accessing elements. 
      outputBlock.Text += String.Format("For key = \"rtf\", value = {0}.",
          openWith["rtf"]) + "\n";

      // The indexer can be used to change the value associated
      // with a key.
      openWith["rtf"] = "winword.exe";
      outputBlock.Text += String.Format("For key = \"rtf\", value = {0}.",
          openWith["rtf"]) + "\n";

      // If a key does not exist, setting the indexer for that key
      // adds a new key/value pair.
      openWith["doc"] = "winword.exe";

      // The indexer throws an exception if the requested key is
      // not in the dictionary.
      try
      {
         outputBlock.Text += String.Format("For key = \"tif\", value = {0}.",
             openWith["tif"]) + "\n";
      }
      catch (KeyNotFoundException)
      {
         outputBlock.Text += "Key = \"tif\" is not found." + "\n";
      }

      // When a program often has to try keys that turn out not to
      // be in the dictionary, TryGetValue can be a more efficient 
      // way to retrieve values.
      string value = "";
      if (openWith.TryGetValue("tif", out value))
      {
         outputBlock.Text += String.Format("For key = \"tif\", value = {0}.", value) + "\n";
      }
      else
      {
         outputBlock.Text += "Key = \"tif\" is not found." + "\n";
      }

      // ContainsKey can be used to test keys before inserting 
      // them.
      if (!openWith.ContainsKey("ht"))
      {
         openWith.Add("ht", "hypertrm.exe");
         outputBlock.Text += String.Format("Value added for key = \"ht\": {0}",
             openWith["ht"]) + "\n";
      }

      // When you use foreach to enumerate dictionary elements,
      // the elements are retrieved as KeyValuePair objects.
      outputBlock.Text += "\n";
      foreach (KeyValuePair<string, string> kvp in openWith)
      {
         outputBlock.Text += String.Format("Key = {0}, Value = {1}",
             kvp.Key, kvp.Value) + "\n";
      }

      // To get the values alone, use the Values property.
      ICollection<string> icoll = openWith.Values;

      // The elements of the ValueCollection are strongly typed
      // with the type that was specified for dictionary values.
      outputBlock.Text += "\n";
      foreach (string s in icoll)
      {
         outputBlock.Text += String.Format("Value = {0}", s) + "\n";
      }

      // To get the keys alone, use the Keys property.
      icoll = openWith.Keys;

      // The elements of the ValueCollection are strongly typed
      // with the type that was specified for dictionary values.
      outputBlock.Text += "\n";
      foreach (string s in icoll)
      {
         outputBlock.Text += String.Format("Key = {0}", s) + "\n";
      }

      // Use the Remove method to remove a key/value pair.
      outputBlock.Text += "\nRemove(\"doc\")" + "\n";
      openWith.Remove("doc");

      if (!openWith.ContainsKey("doc"))
      {
         outputBlock.Text += "Key \"doc\" is not found." + "\n";
      }
   }
}

/* This code example produces the following output:

An element with Key = "txt" already exists.
For key = "rtf", value = wordpad.exe.
For key = "rtf", value = winword.exe.
Key = "tif" is not found.
Key = "tif" is not found.
Value added for key = "ht": hypertrm.exe

Key = txt, Value = notepad.exe
Key = bmp, Value = paint.exe
Key = dib, Value = paint.exe
Key = rtf, Value = winword.exe
Key = doc, Value = winword.exe
Key = ht, Value = hypertrm.exe

Value = notepad.exe
Value = paint.exe
Value = paint.exe
Value = winword.exe
Value = winword.exe
Value = hypertrm.exe

Key = txt
Key = bmp
Key = dib
Key = rtf
Key = doc
Key = ht

Remove("doc")
Key "doc" is not found.
 */

Version Information

Silverlight

Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0

XNA Framework

Supported in: Xbox 360, Windows Phone OS 7.0

Platforms

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

See Also

Reference

System.Collections.Generic Namespace

ICollection<T>

System.Collections