shellmath/add.c

#include <stdio.h>
#ifndef eprintf
#define eprintf(...) fprintf(stderr, __VA_ARGS__)
#endif

int main(int argc, char **argv) {
  int v1;
  int v2;
  int out;
  int e1;
  int e2;

  e1 = sscanf(argv[1], "%i", &v1);
  e2 = sscanf(argv[2], "%i", &v2);
  if(e1==EOF) {
    eprintf("%s: argument 1 cannot be parsed as int", *argv);
    return 1;
  } else if(e2==EOF) {
        eprintf("%s: argument 2 cannot be parsed as int", *argv);
    return 1;
  }
  out=v1+v2;
  printf("%d\n",out);
  return 0;
}