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.NET Framework Class Library
EnumerableToDictionaryTSource, TKey Method (IEnumerableTSource, FuncTSource, TKey, IEqualityComparerTKey)

Creates a DictionaryTKey, TValue from an IEnumerableT according to a specified key selector function and key comparer.

Namespace:   System.Linq
Assembly:  System.Core (in System.Core.dll)
<[%$TOPIC/bb548554_en-us_VS_110_3_0_0_0_0%]> _
Public Shared Function ToDictionary(Of TSource, TKey) ( _
	source As [%$TOPIC/bb548554_en-us_VS_110_3_0_0_0_1%](Of TSource), _
	keySelector As [%$TOPIC/bb548554_en-us_VS_110_3_0_0_0_2%](Of TSource, TKey), _
	comparer As [%$TOPIC/bb548554_en-us_VS_110_3_0_0_0_3%](Of TKey) _
) As [%$TOPIC/bb548554_en-us_VS_110_3_0_0_0_4%](Of TKey, TSource)
public static [%$TOPIC/bb548554_en-us_VS_110_3_0_1_0_0%]<TKey, TSource> ToDictionary<TSource, TKey>(
	this [%$TOPIC/bb548554_en-us_VS_110_3_0_1_0_1%]<TSource> source,
	[%$TOPIC/bb548554_en-us_VS_110_3_0_1_0_2%]<TSource, TKey> keySelector,
	[%$TOPIC/bb548554_en-us_VS_110_3_0_1_0_3%]<TKey> comparer
generic<typename TSource, typename TKey>
static [%$TOPIC/bb548554_en-us_VS_110_3_0_2_0_1%]<TKey, TSource>^ ToDictionary(
	[%$TOPIC/bb548554_en-us_VS_110_3_0_2_0_2%]<TSource>^ source, 
	[%$TOPIC/bb548554_en-us_VS_110_3_0_2_0_3%]<TSource, TKey>^ keySelector, 
	[%$TOPIC/bb548554_en-us_VS_110_3_0_2_0_4%]<TKey>^ comparer
static member ToDictionary : 
        source:[%$TOPIC/bb548554_en-us_VS_110_3_0_3_0_0%]<'TSource> * 
        keySelector:[%$TOPIC/bb548554_en-us_VS_110_3_0_3_0_1%]<'TSource, 'TKey> * 
        comparer:[%$TOPIC/bb548554_en-us_VS_110_3_0_3_0_2%]<'TKey> -> [%$TOPIC/bb548554_en-us_VS_110_3_0_3_0_3%]<'TKey, 'TSource> 
JScript does not support generic types or methods.

Type Parameters


The type of the elements of source.


The type of the keys returned by keySelector.


Type: System.Collections.GenericIEnumerableTSource

An IEnumerableT to create a DictionaryTKey, TValue from.

Type: SystemFuncTSource, TKey

A function to extract a key from each element.

Type: System.Collections.GenericIEqualityComparerTKey

An IEqualityComparerT to compare keys.

Return Value

Type: System.Collections.GenericDictionaryTKey, TSource
A DictionaryTKey, TValue that contains keys and values.

Usage Note

In Visual Basic and C#, you can call this method as an instance method on any object of type IEnumerableTSource. When you use instance method syntax to call this method, omit the first parameter. For more information, see Extension Methods (Visual Basic) or Extension Methods (C# Programming Guide).

source or keySelector is .


keySelector produces a key that is .


keySelector produces duplicate keys for two elements.


If comparer is , the default equality comparer Default is used to compare keys.

Version Information

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

XNA Framework

Supported in: 3.0

Portable Class Library

Supported in: Portable Class Library

Supported in: Windows Phone 8.1

Supported in: Windows Phone Silverlight 8.1

Supported in: Windows Phone Silverlight 8