getopt()
is actually a really simple function. I made a github gist for it, code from here is below too
#include <string.h>
#include <stdio.h>
int opterr = 1, /* if error message should be printed */
optind = 1, /* index into parent argv vector */
optopt, /* character checked for validity */
optreset; /* reset getopt */
char *optarg; /* argument associated with option */
#define BADCH (int)'?'
#define BADARG (int)':'
#define EMSG ""
/*
* getopt --
* Parse argc/argv argument vector.
*/
int
getopt(int nargc, char * const nargv[], const char *ostr)
{
static char *place = EMSG; /* option letter processing */
const char *oli; /* option letter list index */
if (optreset || !*place) { /* update scanning pointer */
optreset = 0;
if (optind >= nargc || *(place = nargv[optind]) != '-') {
place = EMSG;
return (-1);
}
if (place[1] && *++place == '-') { /* found "--" */
++optind;
place = EMSG;
return (-1);
}
} /* option letter okay? */
if ((optopt = (int)*place++) == (int)':' ||
!(oli = strchr(ostr, optopt))) {
/*
* if the user didn't specify '-' as an option,
* assume it means -1.
*/
if (optopt == (int)'-')
return (-1);
if (!*place)
++optind;
if (opterr && *ostr != ':')
(void)printf("illegal option -- %c
", optopt);
return (BADCH);
}
if (*++oli != ':') { /* don't need argument */
optarg = NULL;
if (!*place)
++optind;
}
else { /* need an argument */
if (*place) /* no white space */
optarg = place;
else if (nargc <= ++optind) { /* no arg */
place = EMSG;
if (*ostr == ':')
return (BADARG);
if (opterr)
(void)printf("option requires an argument -- %c
", optopt);
return (BADCH);
}
else /* white space */
optarg = nargv[optind];
place = EMSG;
++optind;
}
return (optopt); /* dump back option letter */
}
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…