#include <graphics.h>
#include <stdlib.h>
#include <conio.h>

main()
{
   int gd, gm, errorcode;

   initgraph(&gd, &gm, "C:\\TC\\BGI");

   errorcode = graphresult();

   if(errorcode != grOk)
   {
      printf("Graphics error: %s\n", grapherrormsg(errorcode));
      printf("Press any key to exit.");
      getch();
      exit(1);
   }

   getch();
   closegraph();
   return 0;
}

In the above program we have not written gd = DETECT.
After running this program we get the output :-
Graphics error: Graphics hardware not detected
Press any key to exit.