Enumerable.ToDictionary<'TSource, 'TKey> Method (IEnumerable<'TSource>, Func<'TSource, 'TKey>)

.NET Framework (current version)

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Creates a Dictionary<'TKey, 'TValue> from an IEnumerable<'T> according to a specified key selector function.

Namespace: System.Linq
Assembly: System.Core (in System.Core.dll)

Syntax

C++

static member ToDictionary<'TSource, 'TKey> : 
        source:IEnumerable<'TSource> *
        keySelector:Func<'TSource, 'TKey> -> Dictionary<'TKey, 'TSource>

Parameters

source: Type: System.Collections.Generic.IEnumerable<'TSource>
An IEnumerable<'T> to create a Dictionary<'TKey, 'TValue> from.

keySelector: Type: System.Func<'TSource, 'TKey>
A function to extract a key from each element.

Return Value

Type: System.Collections.Generic.Dictionary<'TKey, 'TSource>

A Dictionary<'TKey, 'TValue> that contains keys and values.

Type Parameters

TSource: The type of the elements of source.

TKey: The type of the key returned by keySelector.

Exceptions

Exception	Condition
ArgumentNullException	source or keySelector is null. -or- keySelector produces a key that is null.
ArgumentException	keySelector produces duplicate keys for two elements.

Remarks

The ToDictionary<'TSource, 'TKey>(IEnumerable<'TSource>, Func<'TSource, 'TKey>) method uses the default equality comparer Default to compare keys.

Examples

The following code example demonstrates how to use ToDictionary<'TSource, 'TKey>(IEnumerable<'TSource>, Func<'TSource, 'TKey>) to create a Dictionary<'TKey, 'TValue> by using a key selector.

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

Universal Windows Platform
Available since 8
.NET Framework
Available since 3.5
Portable Class Library
Supported in: portable .NET platforms
Silverlight
Available since 2.0
Windows Phone Silverlight
Available since 7.0
Windows Phone
Available since 8.1