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Contract.ForAll(T) Method (IEnumerable(T), Predicate(T))

Determines whether all the elements in a collection exist within a function.

Namespace:  System.Diagnostics.Contracts
Assembly:  mscorlib (in mscorlib.dll)

static member ForAll : 
        collection:IEnumerable<'T> * 
        predicate:Predicate<'T> -> bool

Type Parameters


The type that is contained in collection.


Type: System.Collections.Generic.IEnumerable(T)

The collection from which elements of type T will be drawn to pass to predicate.

Type: System.Predicate(T)

The function to evaluate for the existence of all the elements in collection.

Return Value

Type: System.Boolean
true if and only if predicate returns true for all elements of type T in collection.


collection or predicate is a null reference (Nothing in Visual Basic).

The following example demonstrates how to use the ForAll method to determine whether a collection has a null element.

No code example is currently available or this language may not be supported.

.NET Framework

Supported in: 4.5, 4

.NET Framework Client Profile

Supported in: 4

Portable Class Library

Supported in: Portable Class Library

.NET for Windows Store apps

Supported in: Windows 8

.NET for Windows Phone apps

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

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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