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Task.WhenAll<TResult> Method (Task<TResult>[])

.NET Framework 4.5

Creates a task that will complete when all of the supplied tasks have completed.

Namespace:  System.Threading.Tasks
Assembly:  mscorlib (in mscorlib.dll)
public static Task<TResult[]> WhenAll<TResult>(
	params Task<TResult>[] tasks
)

Type Parameters

TResult

The type of the completed task.

Parameters

tasks
Type: System.Threading.Tasks.Task<TResult>[]

The tasks to wait on for completion.

Return Value

Type: System.Threading.Tasks.Task<TResult[]>
A task that represents the completion of all of the supplied tasks.
ExceptionCondition
ArgumentNullException

The tasks argument was null.

ArgumentException

The tasks array contained a null task.

If any of the supplied tasks completes in a faulted state, the returned task will also complete in a Faulted state, where its exceptions will contain the aggregation of the set of unwrapped exceptions from each of the supplied tasks.

If none of the supplied tasks faulted but at least one of them was canceled, the returned task will end in the Canceled state.

If none of the tasks faulted and none of the tasks were canceled, the resulting task will end in the RanToCompletion state. The Result of the returned task will be set to an array containing all of the results of the supplied tasks in the same order as they were provided (e.g. if the input tasks array contained t1, t2, t3, the output task's Result will return an TResult[] where arr[0] == t1.Result, arr[1] == t2.Result, and arr[2] == t3.Result).

If the supplied array/enumerable contains no tasks, the returned task will immediately transition to a RanToCompletion state before it's returned to the caller. The returned TResult[] will be an array of 0 elements.

.NET Framework

Supported in: 4.5.1, 4.5

.NET for Windows Store apps

Supported in: Windows 8

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone 8, Silverlight 8.1

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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