Gets the next argument option letter that matches recognized option letters.

#include <unistd.h>

char getopt (int argc, char **argv, char optstring);
char *optarg /* Global variables affected by getopt */ int optind

Parameters

argc, argv

Standard command line arguments passed to main.

optstring

A string of recognized option letters.

Remarks

This function compares command line arguments found in argv with optstring. The found argument is indicated in the global variables optarg and optind, where optarg points to the argument, and optind is set to the argv index of the next argument on the command line. On return from getopt, optarg is set to point to the start of the option argument, if any.

If a letter in optstring is followed by a colon, the option is expected to have an argument that may be separated by white space in the command line.

Return Values

• The next letter in argv that matches a letter in optstring.
• EOF when all options are processed.

Requirements