IDictionary<TKey, TValue> Interface

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 propertySupported by the XNA FrameworkSupported by Portable Class LibraryCountGets the number of elements contained in the ICollection<T>. (Inherited from ICollection<T>.)
Public propertySupported by the XNA FrameworkSupported by Portable Class LibraryIsReadOnlyGets a value indicating whether the ICollection<T> is read-only. (Inherited from ICollection<T>.)
Public propertySupported by the XNA FrameworkSupported by Portable Class LibraryItemGets or sets the element with the specified key.
Public propertySupported by the XNA FrameworkSupported by Portable Class LibraryKeysGets an ICollection<T> containing the keys of the IDictionary<TKey, TValue>.
Public propertySupported by the XNA FrameworkSupported by Portable Class LibraryValuesGets an ICollection<T> containing the values in the IDictionary<TKey, TValue>.
Top

  NameDescription
Public methodSupported by the XNA FrameworkSupported by Portable Class LibraryAdd(T)Adds an item to the ICollection<T>. (Inherited from ICollection<T>.)
Public methodSupported by the XNA FrameworkSupported by Portable Class LibraryAdd(TKey, TValue)Adds an element with the provided key and value to the IDictionary<TKey, TValue>.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibraryClearRemoves all items from the ICollection<T>. (Inherited from ICollection<T>.)
Public methodSupported by the XNA FrameworkSupported by Portable Class LibraryContainsDetermines whether the ICollection<T> contains a specific value. (Inherited from ICollection<T>.)
Public methodSupported by the XNA FrameworkSupported by Portable Class LibraryContainsKeyDetermines whether the IDictionary<TKey, TValue> contains an element with the specified key.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibraryCopyToCopies the elements of the ICollection<T> to an Array, starting at a particular Array index. (Inherited from ICollection<T>.)
Public methodSupported by the XNA FrameworkSupported by Portable Class LibraryGetEnumeratorReturns an enumerator that iterates through the collection. (Inherited from IEnumerable<T>.)
Public methodSupported by the XNA FrameworkSupported by Portable Class LibraryRemove(T)Removes the first occurrence of a specific object from the ICollection<T>. (Inherited from ICollection<T>.)
Public methodSupported by the XNA FrameworkSupported by Portable Class LibraryRemove(TKey)Removes the element with the specified key from the IDictionary<TKey, TValue>.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibraryTryGetValueGets the value associated with the specified key.
Top

  NameDescription
Public Extension MethodSupported by the XNA FrameworkSupported by Portable Class LibraryAggregate<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryAggregate<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryAggregate<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryAll<KeyValuePair<TKey, TValue>>Determines whether all elements of a sequence satisfy a condition. (Defined by Enumerable.)
Public Extension MethodSupported by the XNA FrameworkSupported by Portable Class LibraryAny<KeyValuePair<TKey, TValue>>()Overloaded. Determines whether a sequence contains any elements. (Defined by Enumerable.)
Public Extension MethodSupported by the XNA FrameworkSupported by Portable Class LibraryAny<KeyValuePair<TKey, TValue>>(Func<KeyValuePair<TKey, TValue>, Boolean>)Overloaded. Determines whether any element of a sequence satisfies a condition. (Defined by Enumerable.)
Public Extension MethodSupported by the XNA FrameworkSupported by Portable Class LibraryAsEnumerable<KeyValuePair<TKey, TValue>>Returns the input typed as IEnumerable<T>. (Defined by Enumerable.)
Public Extension MethodAsParallel()Overloaded. Enables parallelization of a query. (Defined by ParallelEnumerable.)
Public Extension MethodAsParallel<KeyValuePair<TKey, TValue>>()Overloaded. Enables parallelization of a query. (Defined by ParallelEnumerable.)
Public Extension MethodSupported by Portable Class LibraryAsQueryable()Overloaded. Converts an IEnumerable to an IQueryable. (Defined by Queryable.)
Public Extension MethodSupported by Portable Class LibraryAsQueryable<KeyValuePair<TKey, TValue>>()Overloaded. Converts a generic IEnumerable<T> to a generic IQueryable<T>. (Defined by Queryable.)
Public Extension MethodSupported by the XNA FrameworkSupported by Portable Class LibraryAverage<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryAverage<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryAverage<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryAverage<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryAverage<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryAverage<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryAverage<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryAverage<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryAverage<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryAverage<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryCast<TResult>Casts the elements of an IEnumerable to the specified type. (Defined by Enumerable.)
Public Extension MethodSupported by the XNA FrameworkSupported by Portable Class LibraryConcat<KeyValuePair<TKey, TValue>>Concatenates two sequences. (Defined by Enumerable.)
Public Extension MethodSupported by the XNA FrameworkSupported by Portable Class LibraryContains<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryContains<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryCount<KeyValuePair<TKey, TValue>>()Overloaded. Returns the number of elements in a sequence. (Defined by Enumerable.)
Public Extension MethodSupported by the XNA FrameworkSupported by Portable Class LibraryCount<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryDefaultIfEmpty<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryDefaultIfEmpty<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryDistinct<KeyValuePair<TKey, TValue>>()Overloaded. Returns distinct elements from a sequence by using the default equality comparer to compare values. (Defined by Enumerable.)
Public Extension MethodSupported by the XNA FrameworkSupported by Portable Class LibraryDistinct<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryElementAt<KeyValuePair<TKey, TValue>>Returns the element at a specified index in a sequence. (Defined by Enumerable.)
Public Extension MethodSupported by the XNA FrameworkSupported by Portable Class LibraryElementAtOrDefault<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryExcept<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryExcept<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryFirst<KeyValuePair<TKey, TValue>>()Overloaded. Returns the first element of a sequence. (Defined by Enumerable.)
Public Extension MethodSupported by the XNA FrameworkSupported by Portable Class LibraryFirst<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryFirstOrDefault<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryFirstOrDefault<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryGroupBy<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryGroupBy<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryGroupBy<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryGroupBy<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryGroupBy<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryGroupBy<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryGroupBy<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryGroupBy<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryGroupJoin<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryGroupJoin<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryIntersect<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryIntersect<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryJoin<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryJoin<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryLast<KeyValuePair<TKey, TValue>>()Overloaded. Returns the last element of a sequence. (Defined by Enumerable.)
Public Extension MethodSupported by the XNA FrameworkSupported by Portable Class LibraryLast<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryLastOrDefault<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryLastOrDefault<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryLongCount<KeyValuePair<TKey, TValue>>()Overloaded. Returns an Int64 that represents the total number of elements in a sequence. (Defined by Enumerable.)
Public Extension MethodSupported by the XNA FrameworkSupported by Portable Class LibraryLongCount<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryMax<KeyValuePair<TKey, TValue>>()Overloaded. Returns the maximum value in a generic sequence. (Defined by Enumerable.)
Public Extension MethodSupported by the XNA FrameworkSupported by Portable Class LibraryMax<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryMax<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryMax<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryMax<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryMax<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryMax<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryMax<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryMax<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryMax<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryMax<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryMax<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryMin<KeyValuePair<TKey, TValue>>()Overloaded. Returns the minimum value in a generic sequence. (Defined by Enumerable.)
Public Extension MethodSupported by the XNA FrameworkSupported by Portable Class LibraryMin<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryMin<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryMin<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryMin<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryMin<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryMin<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryMin<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryMin<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryMin<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryMin<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryMin<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryOfType<TResult>Filters the elements of an IEnumerable based on a specified type. (Defined by Enumerable.)
Public Extension MethodSupported by the XNA FrameworkSupported by Portable Class LibraryOrderBy<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryOrderBy<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryOrderByDescending<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryOrderByDescending<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryReverse<KeyValuePair<TKey, TValue>>Inverts the order of the elements in a sequence. (Defined by Enumerable.)
Public Extension MethodSupported by the XNA FrameworkSupported by Portable Class LibrarySelect<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibrarySelect<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibrarySelectMany<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibrarySelectMany<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibrarySelectMany<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibrarySelectMany<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibrarySequenceEqual<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibrarySequenceEqual<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibrarySingle<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibrarySingle<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibrarySingleOrDefault<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibrarySingleOrDefault<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibrarySkip<KeyValuePair<TKey, TValue>>Bypasses a specified number of elements in a sequence and then returns the remaining elements. (Defined by Enumerable.)
Public Extension MethodSupported by the XNA FrameworkSupported by Portable Class LibrarySkipWhile<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibrarySkipWhile<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibrarySum<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibrarySum<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibrarySum<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibrarySum<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibrarySum<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibrarySum<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibrarySum<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibrarySum<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibrarySum<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibrarySum<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryTake<KeyValuePair<TKey, TValue>>Returns a specified number of contiguous elements from the start of a sequence. (Defined by Enumerable.)
Public Extension MethodSupported by the XNA FrameworkSupported by Portable Class LibraryTakeWhile<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryTakeWhile<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryToArray<KeyValuePair<TKey, TValue>>Creates an array from a IEnumerable<T>. (Defined by Enumerable.)
Public Extension MethodSupported by the XNA FrameworkSupported by Portable Class LibraryToDictionary<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryToDictionary<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryToDictionary<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryToDictionary<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryToList<KeyValuePair<TKey, TValue>>Creates a List<T> from an IEnumerable<T>. (Defined by Enumerable.)
Public Extension MethodSupported by the XNA FrameworkSupported by Portable Class LibraryToLookup<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryToLookup<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryToLookup<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryToLookup<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryUnion<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryUnion<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 MethodSupported by the XNA FrameworkSupported by Portable Class LibraryWhere<KeyValuePair<TKey, TValue>>(Func<KeyValuePair<TKey, TValue>, Boolean>)Overloaded. Filters a sequence of values based on a predicate. (Defined by Enumerable.)
Public Extension MethodSupported by the XNA FrameworkSupported by Portable Class LibraryWhere<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>Applies a specified function to the corresponding elements of two sequences, producing a sequence of the results. (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)
{
    Console.WriteLine("Key = {0}, Value = {1}", kvp.Key, kvp.Value);
}


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 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 Main()
    {
        // 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)
        {
            Console.WriteLine("An element with Key = \"txt\" already exists.");
        }

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

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

        // 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
        {
            Console.WriteLine("For key = \"tif\", value = {0}.", 
                openWith["tif"]);
        }
        catch (KeyNotFoundException)
        {
            Console.WriteLine("Key = \"tif\" is not found.");
        }

        // 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))
        {
            Console.WriteLine("For key = \"tif\", value = {0}.", value);
        }
        else
        {
            Console.WriteLine("Key = \"tif\" is not found.");
        }

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

        // When you use foreach to enumerate dictionary elements,
        // the elements are retrieved as KeyValuePair objects.
        Console.WriteLine();
        foreach( KeyValuePair<string, string> kvp in openWith )
        {
            Console.WriteLine("Key = {0}, Value = {1}", 
                kvp.Key, kvp.Value);
        }

        // 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.
        Console.WriteLine();
        foreach( string s in icoll )
        {
            Console.WriteLine("Value = {0}", 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.
        Console.WriteLine();
        foreach( string s in icoll )
        {
            Console.WriteLine("Key = {0}", s);
        }

        // Use the Remove method to remove a key/value pair.
        Console.WriteLine("\nRemove(\"doc\")");
        openWith.Remove("doc");

        if (!openWith.ContainsKey("doc"))
        {
            Console.WriteLine("Key \"doc\" is not found.");
        }
    }
}

/* 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.
 */


.NET Framework

Supported in: 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.
Was this page helpful?
(1500 characters remaining)
Thank you for your feedback

Community Additions

ADD
Show:
© 2014 Microsoft