Count(TSource) Method (IEnumerable(TSource))

Enumerable.Count<'TSource> Method (IEnumerable<'TSource>)


Returns the number of elements in a sequence.

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

static member Count<'TSource> : 
        source:IEnumerable<'TSource> -> int


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

A sequence that contains elements to be counted.

Return Value

Type: System.Int32

The number of elements in the input sequence.

Type Parameters


The type of the elements of source.

Exception Condition

source is null.


The number of elements in source is larger than MaxValue.

If the type of source implements ICollection<'T>, that implementation is used to obtain the count of elements. Otherwise, this method determines the count.

Use the LongCount<'TSource> method when you expect and want to allow the result to be greater than MaxValue.

In Visual Basic query expression syntax, an Aggregate Into Count() clause translates to an invocation of Count.

The following code example demonstrates how to use Count<'TSource>(IEnumerable<'TSource>) to count the elements in an array.

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

Universal Windows Platform
Available since 4.5
.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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