Basic Command-line Option Parsing

Special portable re-entrant version of getopt. More...

Collaboration diagram for Basic Command-line Option Parsing:

Files
file	getopt.h

Functions
int	bu_getopt (int nargc, char *const nargv[], const char *ostr)

Variables
int	bu_opterr
int	bu_optind
int	bu_optopt
char *	bu_optarg

Detailed Description

Special portable re-entrant version of getopt.

Everything is prefixed with bu_, to distinguish it from the various getopt routines found in libc.

Important note - If bu_getopt() is going to be used more than once, it is necessary to reinitialize bu_optind=1 before beginning on the next argument list.

Function Documentation

bu_getopt()

int bu_getopt	(	int	nargc,
		char *const	nargv[],
		const char *	ostr
	)

Get option letter from argument vector.

Parameters

nargc	number of arguments
nargv	array of argument strings
ostr	option string

The 'ostr' option string may contain individual characters (e.g., "abc"), characters followed by a colon to indicate a required argument (e.g., "a:bc", 'a' requires an argument, 'b' and 'c' do not), and characters followed by two colons to indicate an optional argument (e.g., "ab::c", 'b' may be followed by an argument, but none require an argument).

Returns -1 when the argument list is exhausted, otherwise it returns the next known option character. If bu_getopt() encounters a character not found in ostr or if it detects a required missing option argument, it returns ‘?’ (question mark). If ostr has a leading ‘:’ then a missing option argument causes ‘:’ to be returned instead of ‘?’. In either case, the variable bu_optopt is set to the character that caused the error.

Variable Documentation

bu_opterr

int bu_opterr

extern

for bu_getopt(). set to zero to suppress errors.

bu_optind

int bu_optind

extern

for bu_getopt(). current index into parent argv vector.

bu_optopt

int bu_optopt

extern

for bu_getopt(). current option being checked for validity.

bu_optarg

char* bu_optarg

extern

for bu_getopt(). current argument associated with current option.