Enumerable.Concat<'TSource> Method (IEnumerable<'TSource>, IEnumerable<'TSource>)


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Concatenates two sequences.

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

static member Concat<'TSource> : 
        first:IEnumerable<'TSource> *
        second:IEnumerable<'TSource> -> IEnumerable<'TSource>


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

The first sequence to concatenate.

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

The sequence to concatenate to the first sequence.

Return Value

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

An IEnumerable<'T> that contains the concatenated elements of the two input sequences.

Type Parameters


The type of the elements of the input sequences.

Exception Condition

first or second is null.

This method is implemented by using deferred execution. The immediate return value is an object that stores all the information that is required to perform the action. The query represented by this method is not executed until the object is enumerated either by calling its GetEnumerator method directly or by using foreach in Visual C# or For Each in Visual Basic.

The Concat<'TSource>(IEnumerable<'TSource>, IEnumerable<'TSource>) method differs from the Union<'TSource> method because the Concat<'TSource>(IEnumerable<'TSource>, IEnumerable<'TSource>) method returns all the original elements in the input sequences. The Union<'TSource> method returns only unique elements.

The following code example demonstrates how to use Concat<'TSource>(IEnumerable<'TSource>, IEnumerable<'TSource>) to concatenate two sequences.

No code example is currently available or this language may not be supported.

An alternative way of concatenating two sequences is to construct a collection, for example an array, of sequences and then apply the SelectMany<'TSource, 'TResult> method, passing it the identity selector function. The following example demonstrates this use of SelectMany<'TSource, 'TResult>.

No code example is currently available or this language may not be supported.

Universal Windows Platform
Available since 8
.NET Framework
Available since 3.5
Portable Class Library
Supported in: portable .NET platforms
Available since 2.0
Windows Phone Silverlight
Available since 7.0
Windows Phone
Available since 8.1
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