getopt

早期freebsd实现

/*
 * Main/getopt(3) fragment.
 *
 *	@(#)getopt	5.4 (Berkeley) 3/30/94
 */

#include <sys/types.h>

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

void usage __P((void));

int
main(argc, argv)
	int argc;
	char *argv[];
{
	int ch;

	while ((ch = getopt(argc, argv, "")) != EOF)
		switch (ch) {
		case '':
			break;
		case '?':
		default:
			usage();
		}
	argc -= optind;
	argv += optind;
}

void
usage()
{
	(void)fprintf(stderr, "usage: program [-abc] [-f file]\n");
	exit(1);
}