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)
public: generic<typename TSource> [ExtensionAttribute] static TSource Single( IEnumerable<TSource>^ 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.
Type Parameters
- TSource
The type of the elements of source.
| Exception | Condition |
|---|---|
| ArgumentNullException | source is null. |
| 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 null when the input sequence is empty, use SingleOrDefault<TSource>.
The following code example demonstrates how to use Single<TSource>(IEnumerable<TSource>^) to select the only element of an array.
The following code example demonstrates that Single<TSource>(IEnumerable<TSource>^) throws an exception when the sequence does not contain exactly one element.
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