This program doesn’t use any options or arguments, it uses argp to be compliant with the GNU standard command line format.
In addition to giving no arguments and implementing a ‘--help’ option, this example has a ‘--version’ option, which will put the given documentation string and bug address in the ‘--help’ output, as per GNU standards.
The variable argp
contains the argument parser
specification. Adding fields to this structure is the way most
parameters are passed to argp_parse
. The first three fields are
normally used, but they are not in this small program. There are also
two global variables that argp can use defined here,
argp_program_version
and argp_program_bug_address
. They
are considered global variables because they will almost always be
constant for a given program, even if they use different argument
parsers for various tasks.
/* This program doesn’t use any options or arguments, but uses argp to be compliant with the GNU standard command line format. In addition to making sure no arguments are given, and implementing a –help option, this example will have a –version option, and will put the given documentation string and bug address in the –help output, as per GNU standards. The variable ARGP contains the argument parser specification; adding fields to this structure is the way most parameters are passed to argp_parse (the first three fields are usually used, but not in this small program). There are also two global variables that argp knows about defined here, ARGP_PROGRAM_VERSION and ARGP_PROGRAM_BUG_ADDRESS (they are global variables because they will almost always be constant for a given program, even if it uses different argument parsers for various tasks). */ #include <stdlib.h> #include <argp.h> const char *argp_program_version = "argp-ex2 1.0"; const char *argp_program_bug_address = "<bug-gnu-utils@gnu.org>"; /* Program documentation. */ static char doc[] = "Argp example #2 -- a pretty minimal program using argp"; /* Our argument parser. Theoptions
,parser
, andargs_doc
fields are zero because we have neither options or arguments;doc
andargp_program_bug_address
will be used in the output for ‘--help’, and the ‘--version’ option will print outargp_program_version
. */ static struct argp argp = { 0, 0, 0, doc }; int main (int argc, char **argv) { argp_parse (&argp, argc, argv, 0, 0, 0); exit (0); }