A getopt.c for your amusement
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/* An implementation of getopt() by Amrit Prem */
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#include <stdio.h>
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#include <string.h>
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#define bool int
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#define TRUE 1
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#define FALSE 0
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#define EOS '\0'
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bool opterr = TRUE; /* generate error messages */
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int optind = 1; /* index into argv array */
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char * optarg = NULL; /* optional argument */
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int getopt(int argc, char *argv[], const char optstring[])
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{
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static char *opt_ptr = "";
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register char *ptr;
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int option;
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if (*opt_ptr == EOS) {
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if (optind >= argc || argv[optind][0] != '-')
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return -1;
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else if (strcmp(argv[optind], "--") == 0) {
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++optind;
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return -1;
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}
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opt_ptr = argv[optind++] + 1;
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}
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if ((ptr = strchr(optstring, option = *opt_ptr++)) == NULL) {
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if (opterr)
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fprintf(stderr, "Unknown option: -%c\n", option);
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return '?';
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}
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if (*(ptr + 1) == ':') {
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if (optind >= argc) {
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if (opterr)
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fprintf(stderr, "Argument expected for the -%c option\n", option);
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return '?';
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}
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optarg = argv[optind++];
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}
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return option;
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}
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