IReadOnlyDictionary<TKey,TValue>.ContainsKey(TKey) Method

Reference

Definition

Namespace:: System.Collections.Generic

Assemblies:: mscorlib.dll, System.Runtime.dll

Assemblies:: netstandard.dll, System.Runtime.dll

Assembly:: System.Runtime.dll

Assembly:: mscorlib.dll

Assembly:: netstandard.dll

Important

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Determines whether the read-only dictionary contains an element that has the specified key.

public:
 bool ContainsKey(TKey key);

public bool ContainsKey(TKey key);

abstract member ContainsKey : 'Key -> bool

Public Function ContainsKey (key As TKey) As Boolean

Parameters

key: TKey

The key to locate.

Returns

Boolean

true if the read-only dictionary contains an element that has the specified key; otherwise, false.

Exceptions

ArgumentNullException

key is null.

Remarks

Implementations can vary in how they determine the equality of objects; for example, the class that implements IReadOnlyDictionary<TKey,TValue> might use the Comparer<T>.Default property, or it might implement the IComparer<T> method.

Implementations can vary in whether they allow key to be null.

Applies to

Product	Versions
.NET	Core 1.0, Core 1.1, Core 2.0, Core 2.1, Core 2.2, Core 3.0, Core 3.1, 5, 6, 7, 8, 9, 10
.NET Framework	4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1
.NET Standard	1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 2.0, 2.1
UWP	10.0

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