Observable.TakeWhile<TSource> Method (IObservable<TSource>, Func<TSource, Int32, Boolean>)

Returns values from an observable sequence as long as a specified condition is true, and then skips the remaining values.

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


<ExtensionAttribute> _
Public Shared Function TakeWhile(Of TSource) ( _
    source As IObservable(Of TSource), _
    predicate As Func(Of TSource, Integer, Boolean) _
) As IObservable(Of TSource)
Dim source As IObservable(Of TSource)
Dim predicate As Func(Of TSource, Integer, Boolean)
Dim returnValue As IObservable(Of TSource)

returnValue = source.TakeWhile(predicate)
public static IObservable<TSource> TakeWhile<TSource>(
    this IObservable<TSource> source,
    Func<TSource, int, bool> predicate
generic<typename TSource>
static IObservable<TSource>^ TakeWhile(
    IObservable<TSource>^ source, 
    Func<TSource, int, bool>^ predicate
static member TakeWhile : 
        source:IObservable<'TSource> * 
        predicate:Func<'TSource, int, bool> -> IObservable<'TSource> 
JScript does not support generic types and methods.

Type Parameters

  • TSource
    The type source.


  • predicate
    Type: System.Func<TSource, Int32, Boolean>
    True to the function to test each element for a condition; the second parameter of the function represents the index of the source element; otherwise, false.

Return Value

Type: System.IObservable<TSource>
An observable sequence that contains the elements from the input sequence that occur before the element at which the test no longer passes.

Usage Note

In Visual Basic and C#, you can call this method as an instance method on any object of type IObservable<TSource>. When you use instance method syntax to call this method, omit the first parameter. For more information, see or .

See Also


Observable Class

TakeWhile Overload

System.Reactive.Linq Namespace