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Enumerable::SingleOrDefault<TSource> Method (IEnumerable<TSource>^, Func<TSource, Boolean>^)

.NET Framework (current version)

Other Versions

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)

Syntax

C++

public:
generic<typename TSource>
[ExtensionAttribute]
static TSource SingleOrDefault(
	IEnumerable<TSource>^ source,
	Func<TSource, bool>^ predicate
)

Parameters

source: Type: System.Collections.Generic::IEnumerable<TSource>^
An IEnumerable<T> to return a single element from.

predicate: 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

TSource: The type of the elements of source.

Exceptions

Exception	Condition
ArgumentNullException	source or predicate is null.

Remarks

The default value for reference and nullable types is null.

Examples

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.

C++

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.

C++