QProcess control software startup

 Restrictions can only start once the software:

    QSharedMemory mem ( "untitled"); written in the main function:

    if(!mem.create(1))

        QMessageBox::about(0,"启动失败","An instance is running");

    return 0; // essential

Start external software:

  (1) QProcess * p = new QProcess; // start external software

           p->start("D:/a/untitled/debug/untitled.exe");

 （2）QProcess::startDetached("D:/a/build-untitled1-Desktop_Qt_5_5_1_MinGW_32bit-Debug/debug/untitled1");

  

Software Restart: Close the current software .close or qApp-> quiet; then start an external program;