IDictionary<TKey, TValue> Interface

May 11, 2014

Represents a generic collection of key/value pairs.

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

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.

  NameDescription
Public propertyCountGets the number of elements contained in the ICollection<T>. (Inherited from ICollection<T>.)
Public propertyIsReadOnlyGets a value indicating whether the ICollection<T> is read-only. (Inherited from ICollection<T>.)
Public propertyItemGets or sets the element with the specified key.
Public propertyKeysGets an ICollection<T> containing the keys of the IDictionary<TKey, TValue>.
Public propertyValuesGets an ICollection<T> containing the values in the IDictionary<TKey, TValue>.
Top

  NameDescription
Public methodAdd(T)Adds an item to the ICollection<T>. (Inherited from ICollection<T>.)
Public methodAdd(TKey, TValue)Adds an element with the provided key and value to the IDictionary<TKey, TValue>.
Public methodClearRemoves all items from the ICollection<T>. (Inherited from ICollection<T>.)
Public methodContainsDetermines whether the ICollection<T> contains a specific value. (Inherited from ICollection<T>.)
Public methodContainsKeyDetermines whether the IDictionary<TKey, TValue> contains an element with the specified key.
Public methodCopyToCopies the elements of the ICollection<T> to an Array, starting at a particular Array index. (Inherited from ICollection<T>.)
Public methodGetEnumerator()Returns an enumerator that iterates through a collection. (Inherited from IEnumerable.)
Public methodGetEnumerator()Returns an enumerator that iterates through the collection. (Inherited from IEnumerable<T>.)
Public methodRemove(T)Removes the first occurrence of a specific object from the ICollection<T>. (Inherited from ICollection<T>.)
Public methodRemove(TKey)Removes the element with the specified key from the IDictionary<TKey, TValue>.
Public methodTryGetValueGets the value associated with the specified key.
Top

  NameDescription
Public Extension MethodAggregate<KeyValuePair<TKey, TValue>>(Func<KeyValuePair<TKey, TValue>, KeyValuePair<TKey, TValue>, KeyValuePair<TKey, TValue>>)Overloaded. Applies an accumulator function over a sequence. (Defined by Enumerable.)
Public Extension MethodAggregate<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.)
Public Extension MethodAggregate<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.)
Public Extension MethodAll<KeyValuePair<TKey, TValue>>Determines whether all elements of a sequence satisfy a condition. (Defined by Enumerable.)
Public Extension MethodAny<KeyValuePair<TKey, TValue>>()Overloaded. Determines whether a sequence contains any elements. (Defined by Enumerable.)
Public Extension MethodAny<KeyValuePair<TKey, TValue>>(Func<KeyValuePair<TKey, TValue>, Boolean>)Overloaded. Determines whether any element of a sequence satisfies a condition. (Defined by Enumerable.)
Public Extension MethodAsEnumerable<KeyValuePair<TKey, TValue>>Returns the input typed as IEnumerable<T>. (Defined by Enumerable.)
Public Extension MethodAsQueryable()Overloaded. Converts an IEnumerable to an IQueryable. (Defined by Queryable.)
Public Extension MethodAsQueryable<KeyValuePair<TKey, TValue>>()Overloaded. Converts a generic IEnumerable<T> to a generic IQueryable<T>. (Defined by Queryable.)
Public Extension MethodAverage<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.)
Public Extension MethodAverage<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.)
Public Extension MethodAverage<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.)
Public Extension MethodAverage<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.)
Public Extension MethodAverage<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.)
Public Extension MethodAverage<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.)
Public Extension MethodAverage<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.)
Public Extension MethodAverage<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.)
Public Extension MethodAverage<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.)
Public Extension MethodAverage<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.)
Public Extension MethodCast<TResult>Converts the elements of an IEnumerable to the specified type. (Defined by Enumerable.)
Public Extension MethodConcat<KeyValuePair<TKey, TValue>>Concatenates two sequences. (Defined by Enumerable.)
Public Extension MethodContains<KeyValuePair<TKey, TValue>>(KeyValuePair<TKey, TValue>)Overloaded. Determines whether a sequence contains a specified element by using the default equality comparer. (Defined by Enumerable.)
Public Extension MethodContains<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.)
Public Extension MethodCount<KeyValuePair<TKey, TValue>>()Overloaded. Returns the number of elements in a sequence. (Defined by Enumerable.)
Public Extension MethodCount<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.)
Public Extension MethodDefaultIfEmpty<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.)
Public Extension MethodDefaultIfEmpty<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.)
Public Extension MethodDistinct<KeyValuePair<TKey, TValue>>()Overloaded. Returns distinct elements from a sequence by using the default equality comparer to compare values. (Defined by Enumerable.)
Public Extension MethodDistinct<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.)
Public Extension MethodElementAt<KeyValuePair<TKey, TValue>>Returns the element at a specified index in a sequence. (Defined by Enumerable.)
Public Extension MethodElementAtOrDefault<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.)
Public Extension MethodExcept<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.)
Public Extension MethodExcept<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.)
Public Extension MethodFirst<KeyValuePair<TKey, TValue>>()Overloaded. Returns the first element of a sequence. (Defined by Enumerable.)
Public Extension MethodFirst<KeyValuePair<TKey, TValue>>(Func<KeyValuePair<TKey, TValue>, Boolean>)Overloaded. Returns the first element in a sequence that satisfies a specified condition. (Defined by Enumerable.)
Public Extension MethodFirstOrDefault<KeyValuePair<TKey, TValue>>()Overloaded. Returns the first element of a sequence, or a default value if the sequence contains no elements. (Defined by Enumerable.)
Public Extension MethodFirstOrDefault<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.)
Public Extension MethodGroupBy<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.)
Public Extension MethodGroupBy<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.)
Public Extension MethodGroupBy<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.)
Public Extension MethodGroupBy<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.)
Public Extension MethodGroupBy<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.)
Public Extension MethodGroupBy<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.)
Public Extension MethodGroupBy<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.)
Public Extension MethodGroupBy<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.)
Public Extension MethodGroupJoin<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.)
Public Extension MethodGroupJoin<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.)
Public Extension MethodIntersect<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.)
Public Extension MethodIntersect<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.)
Public Extension MethodJoin<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.)
Public Extension MethodJoin<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.)
Public Extension MethodLast<KeyValuePair<TKey, TValue>>()Overloaded. Returns the last element of a sequence. (Defined by Enumerable.)
Public Extension MethodLast<KeyValuePair<TKey, TValue>>(Func<KeyValuePair<TKey, TValue>, Boolean>)Overloaded. Returns the last element of a sequence that satisfies a specified condition. (Defined by Enumerable.)
Public Extension MethodLastOrDefault<KeyValuePair<TKey, TValue>>()Overloaded. Returns the last element of a sequence, or a default value if the sequence contains no elements. (Defined by Enumerable.)
Public Extension MethodLastOrDefault<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.)
Public Extension MethodLongCount<KeyValuePair<TKey, TValue>>()Overloaded. Returns an Int64 that represents the total number of elements in a sequence. (Defined by Enumerable.)
Public Extension MethodLongCount<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.)
Public Extension MethodMax<KeyValuePair<TKey, TValue>>()Overloaded. Returns the maximum value in a generic sequence. (Defined by Enumerable.)
Public Extension MethodMax<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.)
Public Extension MethodMax<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.)
Public Extension MethodMax<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.)
Public Extension MethodMax<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.)
Public Extension MethodMax<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.)
Public Extension MethodMax<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.)
Public Extension MethodMax<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.)
Public Extension MethodMax<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.)
Public Extension MethodMax<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.)
Public Extension MethodMax<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.)
Public Extension MethodMax<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.)
Public Extension MethodMin<KeyValuePair<TKey, TValue>>()Overloaded. Returns the minimum value in a generic sequence. (Defined by Enumerable.)
Public Extension MethodMin<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.)
Public Extension MethodMin<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.)
Public Extension MethodMin<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.)
Public Extension MethodMin<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.)
Public Extension MethodMin<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.)
Public Extension MethodMin<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.)
Public Extension MethodMin<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.)
Public Extension MethodMin<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.)
Public Extension MethodMin<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.)
Public Extension MethodMin<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.)
Public Extension MethodMin<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.)
Public Extension MethodOfType<TResult>Filters the elements of an IEnumerable based on a specified type. (Defined by Enumerable.)
Public Extension MethodOrderBy<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.)
Public Extension MethodOrderBy<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.)
Public Extension MethodOrderByDescending<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.)
Public Extension MethodOrderByDescending<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.)
Public Extension MethodReverse<KeyValuePair<TKey, TValue>>Inverts the order of the elements in a sequence. (Defined by Enumerable.)
Public Extension MethodSelect<KeyValuePair<TKey, TValue>, TResult>(Func<KeyValuePair<TKey, TValue>, TResult>)Overloaded. Projects each element of a sequence into a new form. (Defined by Enumerable.)
Public Extension MethodSelect<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.)
Public Extension MethodSelectMany<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.)
Public Extension MethodSelectMany<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.)
Public Extension MethodSelectMany<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.)
Public Extension MethodSelectMany<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.)
Public Extension MethodSequenceEqual<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.)
Public Extension MethodSequenceEqual<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.)
Public Extension MethodSingle<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.)
Public Extension MethodSingle<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.)
Public Extension MethodSingleOrDefault<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.)
Public Extension MethodSingleOrDefault<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.)
Public Extension MethodSkip<KeyValuePair<TKey, TValue>>Bypasses a specified number of elements in a sequence and then returns the remaining elements. (Defined by Enumerable.)
Public Extension MethodSkipWhile<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.)
Public Extension MethodSkipWhile<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.)
Public Extension MethodSum<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.)
Public Extension MethodSum<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.)
Public Extension MethodSum<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.)
Public Extension MethodSum<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.)
Public Extension MethodSum<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.)
Public Extension MethodSum<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.)
Public Extension MethodSum<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.)
Public Extension MethodSum<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.)
Public Extension MethodSum<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.)
Public Extension MethodSum<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.)
Public Extension MethodTake<KeyValuePair<TKey, TValue>>Returns a specified number of contiguous elements from the start of a sequence. (Defined by Enumerable.)
Public Extension MethodTakeWhile<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.)
Public Extension MethodTakeWhile<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.)
Public Extension MethodToArray<KeyValuePair<TKey, TValue>>Creates an array from a IEnumerable<T>. (Defined by Enumerable.)
Public Extension MethodToDictionary<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.)
Public Extension MethodToDictionary<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.)
Public Extension MethodToDictionary<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.)
Public Extension MethodToDictionary<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.)
Public Extension MethodToList<KeyValuePair<TKey, TValue>>Creates a List<T> from an IEnumerable<T>. (Defined by Enumerable.)
Public Extension MethodToLookup<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.)
Public Extension MethodToLookup<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.)
Public Extension MethodToLookup<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.)
Public Extension MethodToLookup<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.)
Public Extension MethodUnion<KeyValuePair<TKey, TValue>>(IEnumerable<KeyValuePair<TKey, TValue>>)Overloaded. Produces the set union of two sequences by using the default equality comparer. (Defined by Enumerable.)
Public Extension MethodUnion<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.)
Public Extension MethodWhere<KeyValuePair<TKey, TValue>>(Func<KeyValuePair<TKey, TValue>, Boolean>)Overloaded. Filters a sequence of values based on a predicate. (Defined by Enumerable.)
Public Extension MethodWhere<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.)
Public Extension MethodZip<KeyValuePair<TKey, TValue>, TSecond, TResult>Merges two sequences by using the specified predicate function. (Defined by Enumerable.)
Top

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 null. The value can be null 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) {...}

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

NoteNote:

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.

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.


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.
 */


Windows Phone OS

Supported in: 8.1, 8.0, 7.1, 7.0

Windows Phone

Show:
© 2014 Microsoft