XEnumerableSingleOrDefaultTSource Method (IEnumerableTSource, FuncTSource, Boolean, TSource)

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

Namespace: Linq.Extras
Assembly: Linq.Extras (in Linq.Extras.dll) Version: 5.0.0+96a4f4bfed64095342c5df107c1fe1fb95603ee5

Syntax

Copy

public static TSource SingleOrDefault<TSource>(
	this IEnumerable<TSource> source,
	Func<TSource, bool> predicate,
	TSource defaultValue
)

<ExtensionAttribute>
Public Shared Function SingleOrDefault(Of TSource) ( 
	source As IEnumerable(Of TSource),
	predicate As Func(Of TSource, Boolean),
	defaultValue As TSource
) As TSource

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

Parameters

source: Type: System.Collections.GenericIEnumerableTSource
The sequence to return a single element from.
predicate: Type: SystemFuncTSource, Boolean
A function to test an element for a condition.
defaultValue: Type: TSource
The default value to return if the no element matches the predicate.

Type Parameters

TSource: The type of the elements of source.

Return Value

Type: TSource
The single element of the input sequence that satisfies the condition, or defaultValue if no such element is found.

Usage Note

In Visual Basic and C#, you can call this method as an instance method on any object of type IEnumerableTSource. 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).

Reference

XEnumerable Class

SingleOrDefault Overload

Linq.Extras Namespace