EnumerableFirst Method
 
System_CAPS_noteNote

The .NET API Reference documentation has a new home. Visit the .NET API Browser on docs.microsoft.com to see the new experience.

Returns the first element of a sequence.

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

public static TSource First<TSource>(
	this IEnumerable<TSource> source
)
public:
generic<typename TSource>
[ExtensionAttribute]
static TSource First(
	IEnumerable<TSource>^ source
)
static member First<'TSource> : 
        source:IEnumerable<'TSource> -> 'TSource
<ExtensionAttribute>
Public Shared Function First(Of TSource) (
	source As IEnumerable(Of TSource)
) As TSource

Parameters

source
Type:

The IEnumerable to return the first element of.

Return Value

Type: TSource

The first element in the specified sequence.

Type Parameters

TSource

The type of the elements of source.

Exception Condition
ArgumentNullException

source is null.

InvalidOperationException

The source sequence is empty.

The First 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.

The following code example demonstrates how to use First to return the first element of an array.

int[] numbers = { 9, 34, 65, 92, 87, 435, 3, 54, 
                    83, 23, 87, 435, 67, 12, 19 };

int first = numbers.First();

Console.WriteLine(first);

/*
 This code produces the following output:

 9
*/
' Create an array of integers.
Dim numbers() As Integer =
{9, 34, 65, 92, 87, 435, 3, 54, 83, 23, 87, 435, 67, 12, 19}

' Select the first element in the array.
Dim first As Integer = numbers.First()

' Display the output.
MsgBox(first)

' This code produces the following output:
'
' 9
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
Return to top