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SafeHandle.IsInvalid Property

When overridden in a derived class, gets a value indicating whether the handle value is invalid.

Namespace:  System.Runtime.InteropServices
Assembly:  mscorlib (in mscorlib.dll)

public abstract bool IsInvalid { get; }

Property Value

Type: System.Boolean
true if the handle value is invalid; otherwise, false.

Derived classes must implement the IsInvalid property so that the common language runtime can determine whether critical finalization is required. Derived classes must provide an implementation that suits the general type of handle they support (0 or -1 is invalid). These classes can then be further derived for specific safe handle types.

Unlike the IsClosed property, which reports whether the SafeHandle object has finished using the underlying handle, the IsInvalid property calculates whether the given handle value is always considered invalid. Therefore, the IsInvalid property always returns the same value for any one handle value.

The following example checks if a file was opened successfully. This code example is part of a larger example provided for the SafeHandle class.

// Determine if file is opened successfully. 
if (_handle.IsInvalid)
    throw new Win32Exception(Marshal.GetLastWin32Error(), fileName);

.NET Framework

Supported in: 4.5, 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

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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