Enumerable::Single<TSource> Method (IEnumerable<TSource>)
Returns the only element of a sequence, and throws an exception if there is not exactly one element in the sequence.
Assembly: System.Core (in System.Core.dll)
[ExtensionAttribute] public: generic<typename TSource> static TSource Single( IEnumerable<TSource>^ source )
Type Parameters
- TSource
The type of the elements of source.
Parameters
- source
- Type: System.Collections.Generic::IEnumerable<TSource>
An IEnumerable<T> to return the single element of.
Return Value
Type: TSourceThe single element of the input sequence.
Usage Note
In Visual Basic and C#, you can call this method as an instance method on any object of type IEnumerable<TSource>. 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).| Exception | Condition |
|---|---|
| ArgumentNullException | source is nullptr. |
| InvalidOperationException | The input sequence contains more than one element. -or- The input sequence is empty. |
The Single<TSource>(IEnumerable<TSource>) method throws an exception if the input sequence is empty. To instead return nullptr when the input sequence is empty, use SingleOrDefault.
Windows 7, Windows Vista, Windows XP SP2, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC, Xbox 360, Zune
The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.