#include <stdio.h>
#include <conio.h>            /* Needed for getch ()                       */
main ()
{
char isbn [11] ;
char CheckDigit (char [11]) ; /* While working on the main bit, simply use */
                              /* checkdigit.obj in your project file       */

int choice ;
char dummy ;

do
   {
   /* Display menu here, accept user choice, and act on it. */
   }
while (    ) ;
}

/* Put your version of CheckDigit here. */
/*
char CheckDigit (char isbn [11])
  {
  }
*/