This documentation is archived and is not being maintained.
Enumerable.First(TSource) Method (IEnumerable(TSource))
Visual Studio 2010
Returns the first element of a sequence.
Assembly: System.Core (in System.Core.dll)
Type Parameters
- TSource
The type of the elements of source.
Parameters
- source
- Type: System.Collections.Generic.IEnumerable(TSource)
The IEnumerable(T) to return the first element of.
Return Value
Type: TSourceThe first element in the specified 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 a null reference (Nothing in Visual Basic). |
| InvalidOperationException | The source sequence is empty. |
The First(TSource)(IEnumerable(TSource)) method throws an exception if source contains no elements. To instead return a default value when the source sequence is empty, use the FirstOrDefault method.
Windows 7, Windows Vista SP1 or later, Windows XP SP3, 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.
Show: