#include <stdio.h>
#include <getopt.h>

int main(int argc,char* argv[]) {
/* -h -> help
 * -i input
 * -o [output] */
char* optstring=":hi:o::";
int val;
while (EOF!=(val=getopt(argc,argv,optstring))) {
   switch (val) {
      case 'h': printf("help\n"); break;
      case 'o': printf("output %s\n",optarg); break;
      case 'i': printf("input %s\n",optarg); break;
      case ':': printf("arg missing for option %c\n",optopt); break;
      case '?': printf("unknown option %c\n",optopt); break;
   }
}
return 0;
}