SingleOrDefault(TSource) Method (IEnumerable(TSource), Func(TSource, Boolean))

Enumerable.SingleOrDefault<'TSource> Method (IEnumerable<'TSource>, Func<'TSource, Boolean>)


Returns the only element of a sequence that satisfies a specified condition or a default value if no such element exists; this method throws an exception if more than one element satisfies the condition.

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

static member SingleOrDefault<'TSource> : 
        source:IEnumerable<'TSource> *
        predicate:Func<'TSource, bool> -> 'TSource


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

An IEnumerable<'T> to return a single element from.

Type: System.Func<'TSource, Boolean>

A function to test an element for a condition.

Return Value

Type: TSource

The single element of the input sequence that satisfies the condition, or default(TSource) if no such element is found.

Type Parameters


The type of the elements of source.

Exception Condition

source or predicate is null.

The default value for reference and nullable types is null.

The following code example demonstrates how to use SingleOrDefault<'TSource>(IEnumerable<'TSource>, Func<'TSource, Boolean>) to select the only element of an array that satisfies a condition.

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

The following code example demonstrates that SingleOrDefault<'TSource>(IEnumerable<'TSource>, Func<'TSource, Boolean>) returns a default value when the sequence does not contain exactly one element that satisfies the condition.

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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