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getopt.c
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1994-03-18
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/*
* Copyright (c) 1987, 1989 University of Maryland
* Department of Computer Science. All rights reserved.
* Permission to copy for any purpose is hereby granted
* so long as this copyright notice remains intact.
*/
/*
* getopt - get option letter from argv
* (From Henry Spencer @ U of Toronto Zoology, slightly edited)
*/
#include <stdio.h>
char *optarg; /* Global argument pointer. */
int optind; /* Global argv index. */
static char *scan; /* Private scan pointer. */
extern char *index();
int
getopt(argc, argv, optstring)
register int argc;
register char **argv;
char *optstring;
{
register int c;
register char *place;
optarg = NULL;
if (scan == NULL || *scan == 0) {
if (optind == 0)
optind++;
if (optind >= argc || argv[optind][0] != '-' ||
argv[optind][1] == 0)
return (EOF);
if (strcmp(argv[optind], "--") == 0) {
optind++;
return (EOF);
}
scan = argv[optind] + 1;
optind++;
}
c = *scan++;
place = index(optstring, c);
if (place == NULL || c == ':') {
fprintf(stderr, "%s: unknown option -%c\n", argv[0], c);
return ('?');
}
place++;
if (*place == ':') {
if (*scan != '\0') {
optarg = scan;
scan = NULL;
} else {
if (optind >= argc) {
fprintf(stderr,
"%s: missing argument after -%c\n",
argv[0], c);
return ('?');
}
optarg = argv[optind];
optind++;
}
}
return (c);
}