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Enumerable.Concat(TSource) Method

Concatenates two sequences.

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

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

Type Parameters

TSource

The type of the elements of the input sequences.

Parameters

first
Type: System.Collections.Generic.IEnumerable(TSource)

The first sequence to concatenate.

second
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.

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).

ExceptionCondition
ArgumentNullException

first or second is a null reference (Nothing in Visual Basic).

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 method because the Concat(TSource)(IEnumerable(TSource), IEnumerable(TSource)) method returns all the original elements in the input sequences. The Union 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 method, passing it the identity selector function. The following example demonstrates this use of SelectMany.

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

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

XNA Framework

Supported in: 3.0

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone Silverlight 8.1, Windows Phone Silverlight 8

Portable Class Library

Supported in: Portable Class Library
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