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Observable.FirstOrDefault(Of TSource) Method (IObservable(Of TSource))

Returns the first element of an observable sequence, or a default value if no value is found.

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

'Declaration
<ExtensionAttribute> _
Public Shared Function FirstOrDefault(Of TSource) ( _
	source As IObservable(Of TSource) _
) As TSource
'Usage
Dim source As IObservable(Of TSource)
Dim returnValue As TSource

returnValue = source.FirstOrDefault()

Type Parameters

TSource

The type of source.

Parameters

source
Type: System.IObservable(Of TSource)
The source observable sequence.

Return Value

Type: TSource
The first element in the observable sequence, or a default value if no value is found.

Usage Note

In Visual Basic and C#, you can call this method as an instance method on any object of type IObservable(Of TSource). When you use instance method syntax to call this method, omit the first parameter. For more information, see http://msdn.microsoft.com/en-us/library/bb384936(v=vs.103).aspx or http://msdn.microsoft.com/en-us/library/bb383977(v=vs.103).aspx.
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