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Enumerable.First<TSource> Method (IEnumerable<TSource>)

 
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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
)

Parameters

source
Type: System.Collections.Generic.IEnumerable<TSource>

The IEnumerable<T> 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<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<TSource> method.

The following code example demonstrates how to use First<TSource>(IEnumerable<TSource>) 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
*/

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
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