getopt under Linux

#include <stdio.h> #include <unistd.h> void mygetopt(int argc, char *argv[], const char *optstr) { extern char *optarg; extern int optind, optopt; int ch; printf("/nresult for /"%s/":/n", optstr); while (-1 != (ch = getopt(argc, argv, optstr))) { printf("optind=%.2d ", optind); switch (ch) { case 'a': printf("-%c/n", ch); break; case 'b': case 'c': printf("-%c %s/n", ch, optarg); break; case ':': printf("-%c [need an argument]/n", optopt); break; case '?': printf("-%c [unknown option]/n", optopt); break; default: break; } } } int main(int argc, char *argv[]) { extern int optind, opterr; for (int i=1; i<argc; i++) printf("%s ", argv[i]); printf("/n"); mygetopt(argc, argv, ":ab:c:"); optind = 1; // reset index opterr = 0; // disable error msg in stderr mygetopt(argc, argv, "ab:c:"); return 0; }

 

> ./getoptdemo -ab arg1 -dc

 

 

-ab arg1 -dc

result for ":ab:c:":
optind=01 -a
optind=03 -b arg1
optind=03 -d [unknown option]
optind=04 -c [need an argument]

result for "ab:c:":
optind=01 -a
optind=03 -b arg1
optind=03 -d [unknown option]
optind=04 -c [unknown option]