System Shut down program in c++ using borland

#include <iostream>
       #include <conio>
       #include <windows>

       void main()

       {
        int  opt;
        cout<<"\t\twhich type of window you have\n\t\tEnter one for shoutdown for windows xp\n\t\tEnter 2 for windows 7\n";

        switch(opt)
        {
         case 1:
         system("C:\\WINDOWS \\System32\\shutdown-s-t-0");

         break;
         case 2:
         system("C:\\WINDOWS \\System32\\shutdown/s/t 0");
         break;

        }



       getch();}