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Dictionary<TKey, TValue>.Keys Property

Gets a collection containing the keys in the Dictionary<TKey, TValue>.

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

public Dictionary<(Of <(<'TKey, TValue>)>)>..::..KeyCollection Keys { get; }

The order of the keys in the Dictionary<TKey, TValue>.KeyCollection is unspecified, but it is the same order as the associated values in the Dictionary<TKey, TValue>.ValueCollection returned by the Values property.

The returned Dictionary<TKey, TValue>.KeyCollection is not a static copy; instead, the Dictionary<TKey, TValue>.KeyCollection refers back to the keys in the original Dictionary<TKey, TValue>. Therefore, changes to the Dictionary<TKey, TValue> continue to be reflected in the Dictionary<TKey, TValue>.KeyCollection.

Getting the value of this property is an O(1) operation.

The following code example shows how to enumerate the keys in the dictionary using the Keys property, and how to enumerate the keys and values in the dictionary.

This code is part of a larger example that can be compiled and executed. See Dictionary<TKey, TValue>.


// To get the keys alone, use the Keys property.
Dictionary<string, string>.KeyCollection keyColl =
    openWith.Keys;

// The elements of the KeyCollection are strongly typed
// with the type that was specified for dictionary keys.
Console.WriteLine();
foreach( string s in keyColl )
{
    Console.WriteLine("Key = {0}", s);
}


...


// 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);
}


.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.
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