/* File: mycal3.c

   Step 3 in writing my version of the
   calendar program.  
   This program prints several months,
   all with 31 days.
*/

void PrintOneMonth(int start, int days) ;
int AddDay(int weekday, int inc) ;

main() {
   int start, months, i ;
   int weekday, inc, next ;

   printf("start =? ") ;
   start = GetInteger() ;
   printf("months =? ") ;
   months = GetInteger() ;

   for (i = 0 ; i < months ; i++) {
      PrintOneMonth(start, 31) ;
      start = AddDay(start, 31) ;
   }
}

int AddDay(int weekday, int inc) {
   return( (weekday + inc) % 7 ) ;
}

void PrintOneMonth(int start, int days) {
   int i ;

   /* Indent the first line */
   for (i = 0 ; i < start ; i++) {
      printf("   ") ;
   }

   for (i = 1 ; i <= days ; i++) {
      printf("%3d", i) ;
      /* print newline at end of week */
      if ( (i + start) % 7 == 0 ) {
	 printf("\n") ;
      }
   }

   /* Print newline at end of month
     only if necessary */
   if( (i + start) % 7 != 1)  {
      printf("\n") ;
   }
}