IDictionary(TKey, TValue).ContainsKey Method

Determines whether the IDictionary(TKey, TValue) contains an element with the specified key.

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

No code example is currently available or this language may not be supported.

Parameters

key
Type: TKey
The key to locate in the IDictionary(TKey, TValue).

Return Value

Type: System.Boolean
true if the IDictionary(TKey, TValue) contains an element with the key; otherwise, false.

ExceptionCondition
ArgumentNullException

key is a null reference (Nothing in Visual Basic).

Implementations can vary in how they determine equality of objects; for example, the List(T) class uses Comparer(T).Default, whereas the Dictionary(TKey, TValue) class allows the user to specify the IComparer(T) implementation to use for comparing keys.

Implementations can vary in whether they allow key to be a null reference (Nothing in Visual Basic).

The following code example shows how to use the ContainsKey method to test whether a key exists prior to calling the Add method. It also shows how to use the TryGetValue method, which can be a more efficient way to retrieve values if a program frequently tries key values that are not in the dictionary. Finally, it shows how to insert items using Item property (the indexer in C#).

This code is part of a larger example that can be compiled and executed. See System.Collections.Generic.IDictionary(TKey, TValue).

No code example is currently available or this language may not be supported.

Silverlight

Supported in: 5, 4, 3

Silverlight for Windows Phone

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

XNA Framework

Supported in: Xbox 360, Windows Phone OS 7.0

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

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