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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);

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98

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

.NET Framework

Supported in: 3.5, 3.0, 2.0

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