22.6.2 Accessing Command-line Parameters

If the program was invoked with any command-line arguments, it can access them through the arguments of main, argc and argv. (You can give these arguments any names, but the names argc and argv are customary.)

The value of argv is an array containing all of the command-line arguments as strings, with the name of the command invoked as the first string. argc is an integer that says how many strings argv contains. Here is an example of accessing the command-line parameters, retrieving the program’s name and checking for the standard --version and --help options:

#include <string.h> /* Declare strcmp. */

int
main (int argc, char *argv[])
{
  char *program_name = argv[0];

  for (int i = 1; i < argc; i++)
    {
      if (!strcmp (argv[i], "--version"))
        {
          /* Print version information and exit. */
          …
        }
      else if (!strcmp (argv[i], "--help"))
        {
          /* Print help information and exit. */
          …
        }
    }
  …
}