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Chapter 3 169
Programming Examples
Using C Programming Over Socket LAN (Windows NT)
getopt places in optind the argv index of the next argument to be
processed. The external variable optind is initialized to 1 before
the first call to the function getopt.
When all options have been processed (i.e., up to the first non-option
argument), getopt returns EOF. The special option -- can be used to
delimit the end of the options; EOF is returned, and -- is skipped.
***************************************************************************/
#include <stdio.h> /* For NULL, EOF */
#include <string.h> /* For strchr() */
char *optarg; /* Global argument pointer. */
int optind = 0; /* Global argv index. */
static char *scan = NULL; /* Private scan pointer. */
int getopt( int argc, char * const argv[], const char* optstring)
{
char c;
char *posn;
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);