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.
Assembly: System.Core (in System.Core.dll)
public static TSource SingleOrDefault<TSource>( this 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: TSourceThe 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.
| Exception | Condition |
|---|---|
| ArgumentNullException | 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.
string[] fruits = { "apple", "banana", "mango", "orange", "passionfruit", "grape" }; string fruit1 = fruits.SingleOrDefault(fruit => fruit.Length > 10); Console.WriteLine(fruit1); /* This code produces the following output: passionfruit */
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.
Available since 8
.NET Framework
Available since 3.5
Portable Class Library
Supported in: portable .NET platforms
Silverlight
Available since 2.0
Windows Phone Silverlight
Available since 7.0
Windows Phone
Available since 8.1