Thread: Core Dump in While()

Hey, I'm using the following code:

Code:

   do {
      printf("Start scan\n");
      fscanf(in, "%d%d", &a, &b);
      printf("scanned %d %d\n", a, b);
      if(a !=0 && b!= 0) addDirectedEdge(G, a, b);
      printf("return\n");
   } while(a != 0 || b != 0);
   printf("done");

and I'm getting a core dump immediately after it prints 'return' when it reads in '0 0' from any line in the input. I tried using a counter to have a set number of iterations and it still core dumped when the while loop went false. a and b are ints. Anyone know why this might be happening? Any help would be appreciated.