Task.WaitAny Method (Task[])


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Waits for any of the provided Task objects to complete execution.

Namespace:   System.Threading.Tasks
Assembly:  mscorlib (in mscorlib.dll)

public static int WaitAny(
	params Task[] tasks


Type: System.Threading.Tasks.Task[]

An array of Task instances on which to wait.

Return Value

Type: System.Int32

The index of the completed Task object in the tasks array.

Exception Condition

The Task has been disposed.


The tasks argument is null.


The tasks argument contains a null element.

The following example launches five tasks, each of which sleeps for a minimum of 50 milliseconds or a maximum of 1,050 milliseconds. The WaitAny method then waits for any of the tasks to complete. The example displays the task ID of the task that ended the wait, as well as the current status of all the tasks.

using System;
using System.Threading;
using System.Threading.Tasks;

public class Example
   public static void Main()
      Task[] tasks = new Task[5];
      for (int ctr = 0; ctr <= 4; ctr++) {
         int factor = ctr;
         tasks[ctr] = Task.Run(() => Thread.Sleep(factor * 250 + 50));
      int index = Task.WaitAny(tasks);
      Console.WriteLine("Wait ended because task #{0} completed.",
      Console.WriteLine("\nCurrent Status of Tasks:");
      foreach (var t in tasks)
         Console.WriteLine("   Task {0}: {1}", t.Id, t.Status);
// The example displays output like the following:
//       Wait ended because task #1 completed.
//       Current Status of Tasks:
//          Task 1: RanToCompletion
//          Task 2: Running
//          Task 3: Running
//          Task 4: Running
//          Task 5: Running

Universal Windows Platform
Available since 8
.NET Framework
Available since 4.0
Portable Class Library
Supported in: portable .NET platforms
Available since 5.0
Windows Phone Silverlight
Available since 8.0
Windows Phone
Available since 8.1
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