How to make an application run only one instance

For an application to run only one instance, a simple method is to use mutexes in the application class, which can be generated by the GUIDGEN.EXE program under VC. GUIDGEN.EXE is located in the VC installation directory Commontools directory

Instance

1: Create a new project EX1 based on the dialog box, with the default setting

2: Create a global flag with GUIDGEN.EXE, #define One "generated global flag"

The following statements are generated in this example: #define ONE "0xbe8e2ce1, 0xdab6, 0x11d6, 0xad, 0xd0, 0x0, 0xe0, 0x4c, 0x53, 0xf6, 0xe6"

3: In the Application Class Cex1app::initinstance (), create a mutex with the CreateMutex function, and then call the function GetLastError ()

If the result is equal to error_already_exists the description already has an instance running at this time returns False.bool Cex1app::initinstance () {Handle=::createmutex null,false, one);//handle is a global variable of the declared handle type

if (GetLastError () ==error_already_exists)

{

AfxMessageBox ("The application is already running");

return FALSE;

}

}

4: In Cex1app::exitinstance (), remove this mutex int cex1app::exitinstance () {

CloseHandle (handle);

return CWinApp::ExitInstance ();

}

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