How to compare Command Line Arguments in C like in C++

Question

Normally in C++ I would compare command line options as follows:

#include <string>

int main(int argc, char* argv[])
{
  if (std::string(argv[1]) == "-h") /*Handle -h option*/
  return 0;
}

This works just fine. But is there a way to do something similar in C?

You're looking for [`strcmp`](https://www.cplusplus.com/reference/cstring/strcmp/) — Jabberwocky, May 11 '21 at 11:58
In C++ I often write `std::vector args(argv, argv+argc)`. That converts them all to strings so you don't need to do it on a case by case basis. — MSalters, May 11 '21 at 12:02
Consider using `getopt()` to process command line options instead. — r3mainer, May 11 '21 at 12:07

score 0 · Answer 1 · answered May 11 '21 at 12:05

0

This is just your code converted to C. As C doesn't have the type std::string you have to use character arrays. Those are compared with strcmp.

int main(int argc, char *argv[]) {
    if (strcmp(argv[1], "-h") == 0) /*Handle -h option*/
    return 0;
}

answered May 11 '21 at 12:05

Bananenkönig

score 0 · Answer 2 · answered May 11 '21 at 12:06

You want to #include <string.h> and use strcmp() as in

if (strcmp(argv[1], "-h") == 0) {
    // whatever
}

Or, if you prefer to do it "by hand" with no calls into the C standard library

if ((argv[1][0] == '-') && (argv[1][1] == 'h') && (argv[1][2] == '\0')) {
    // whatever
}

2 Answers2