title: isdigit() Segmentation Fault
body: <p>Getting a weird segmentation fault on following code when I try to pass a number into my application on command line.</p>
  
  <pre><code>int offset = 3;
  
  int main(int argc, char *argv[]) {
      // Check for arguments to see whether there is a custom offset
      if (argc == 2) {
          // If argc == 2 then we have a offset?
          if (isdigit((unsigned char)*argv[1])) {
              offset = atoi(*argv[1]);
              printf("Offset changed to: %d\n", offset);
          } else {
              printf("Offset not changed due to %s not being a number.\n", *argv[1]);
          }
      } else if(argc &gt;= 2) {
          // If argc &gt;= 2 then we have too many arguments
          printf("Too many arguments.");
          return 0;
      }
  }
  </code></pre>