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CreateMutex (coredll)

coredll is for smart devices, not desktop Windows. Therefore, this information only applies to code using the .NET Compact Framework. To see if information for CreateMutex in other DLLs exists, click on Find References to the right.


C# Signature:

[DllImport("coredll.dll", SetLastError=true)]
public static extern int CreateMutex(IntPtr lpMutexAttributes, bool bInitiaOwner, string lpName);
// Not needed due to using the SetLastError=true
// use Marshal.GetLastWin32Error() to retrieve the error.
//public static extern int GetLastError();

User-Defined Types:

const int ERROR_ALREADY_EXISTS = 183;


It should be used in conjunction with Marshal.GetLastWin32Error() to check the application already existed in the process list.

Sample Code:

    private static bool CheckInstance()
        CreateMutex(IntPtr.Zero, true, "<Application Name>"); // to be replaced by the name of your application

        return Marshal.GetLastWin32Error() == ERROR_ALREADY_EXISTS;

CreateMutex on MSDN

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