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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)

abstract IsInvalid : bool

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, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

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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