General Programming Information

getopt:

If you want an easy way to retrieve option letters from a command line such as
```
<executable> -x <some opt> -y <some opt> -z
```
use the getopt function available from the stdlib.

Gary wrote up a nice piece of code for you all to demonstrate how getopt works.

#include <stdlib.h> 
#include <stdio.h>       

void usage(char*);

int arg;
char *str1 = NULL;
char *str2 = NULL;   
        
int main ( int argc, char **argv ) {
  while ( (arg=getopt(argc, argv, "a:b:v")) != EOF ) {
    switch( arg ) {
      case 'a': {
        str1 = optarg;
        continue;
      }
      case 'b': {
        str2 = optarg;
        continue;
      }
      case 'v': {
        printf("version blah blah blah\n");
        exit(0); 
      }
      case '?':  
      default: {
        usage( argv[0] );
        break;
      }
    }
  } 
  if ( str1 != NULL ) {
    printf("-a = '%s'\n", str1); 
  }

  if ( str2 != NULL ) {
    printf("-b = '%s'\n", str2);
  }

  return 0;
}

void usage(char* name) {
  fprintf(stderr, "usage: %s [-a str1 -b str2]\n", name);
  exit(-1);
}