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Marshal.GetLastWin32Error Method

Returns the error code returned by the last unmanaged function called using platform invoke that has the DllImportAttribute.SetLastError flag set.

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

public static int GetLastWin32Error ()
public static int GetLastWin32Error ()
public static function GetLastWin32Error () : int

Return Value

The last error code set by a call to the Win32 SetLastError API method.

GetLastWin32Error exposes the Win32 GetLastError API method from Kernel32.DLL. This method exists because it is not safe to make a direct platform invoke call to GetLastError to obtain this information. If you want to access this error code, you must call GetLastWin32Error rather than writing your own platform invoke definition for GetLastError and calling it. The common language runtime can make internal calls to APIs that overwrite the operating system maintained GetLastError.

You can only use this method to obtain error codes if you apply the System.Runtime.InteropServices.DllImportAttribute to the method signature and set the SetLastError field to true. The process for this varies depending upon the source language used: C# and C++ are false by default, but the Declare statement in Visual Basic is true. For additional information about the GetLastError and SetLastError Win32 API methods, see the MSDN Library.

NoteNote

This method uses SecurityAction.LinkDemand to prevent it from being called from untrusted code; only the immediate caller is required to have SecurityPermissionAttribute.UnmanagedCode permission. If your code can be called from partially trusted code, do not pass user input to Marshal class methods without validation. For important limitations on using the LinkDemand member, see Demand vs. LinkDemand.

The following code example demonstrates calling the GetLastWin32Error method. The code example first demonstrates calling the method with no error present and then demonstrates calling the method with an error present.

using System;
using System.Runtime.InteropServices;

internal class Win32
{
    // Use DllImportAttribute to inport the Win32 MessageBox
    // function.  Set the SetLastError flag to true to allow
    // the function to set the Win32 error.
    [DllImportAttribute("user32.dll", SetLastError=true)]
    public static extern int MessageBox(IntPtr hwnd, String text, String caption, uint type);

}

class Program
{

    static void Run()
    {
        // Call the MessageBox with normal parameters.

        Console.WriteLine("Calling Win32 MessageBox without error...");

        Win32.MessageBox(new IntPtr(0), "Press OK...", "Press OK Dialog", 0);

        // Get the last error and display it.
        int error = Marshal.GetLastWin32Error();

        Console.WriteLine("The last Win32 Error was: " + error);

        // Call the MessageBox with an invalid window handle to
        // produce a Win32 error.

        Console.WriteLine("Calling Win32 MessageBox with error...");

        Win32.MessageBox(new IntPtr(123132), "Press OK...", "Press OK Dialog", 0);

        // Get the last error and display it.

        error = Marshal.GetLastWin32Error();

        Console.WriteLine("The last Win32 Error was: " + error);
    }

    static void Main(string[] args)
    {
        Run();
    }
}
// This code example displays the following to the console: 
//
// Calling Win32 MessageBox without error...
// The last Win32 Error was: 0
// Calling Win32 MessageBox with error...
// The last Win32 Error was: 1400

Windows 98, Windows 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

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

.NET Framework

Supported in: 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 2.0, 1.0

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