liboptions

Easy option parsing.

License

The author disclaims copyright to this source code. In place of a legal notice, here is a blessing:

• May you do good and not evil.
• May you find forgiveness for yourself and forgive others.
• May you share freely, never taking more than you give.

Example

#include <stdlib.h>
#include <stdio.h>
#include "options.h"

static const char *program = "example";
static void help(const char *opt, const char *arg, int l)
{
  printf("Usage: %s ...\n", program);
  exit(1);
}

int main(int argc, char **argv)
{
  int flag_debug = 0;

  program = argv[0];
  parse_options(&argc, &argv, OPTIONS(
    FLAG('d', "debug", flag_debug, 1),
    FLAG_CALLBACK('h', "help", help)
  ));

  printf("Debug: %d\n", flag_debug);

  return 0;
}

Compile with cc -o example example.c options.c.

Usage

int parse_options(int *argc, char ***argv, option_t **options);

The main work is done with the parse_options function. It expects pointers to argc and argv. When the parsing process is complete, argc and argv will be modified to hold only the positional arguments. All the options will be removed.

The third argument is a list of supported options.

The most natural way to use it is like this:

parse_options(&argc, &argv, OPTIONS(
  ...
));

OPTIONS(...)

This macro creates a zero terminated list of options. You can pass any number of options. The options should be created with the option macros.

FLAG(s, l, f, v)

This macro creates a flag option. A Flag has no arguments but sets the variable f to the value v, if it is encountered on the command line. f must be an int lvalue and v an int value.

s and l are always the short and long option names. s must be a char, l must be a c string. If you do not need either the short or the long option, s or l may be set to 0.

FLAG_CALLBACK(s, l, c)

This macro creates a flag option with a callback. Instead of setting a variable, the callback function c is called, if the flag is encountered on the command line.

All callback functions must be of type void c(const char *opt, const char *arg, int l). opt is a c string holding the option name (without leading hyphens), arg is a c string holding the supplied value and l is nonzero, if opt is a long option.

Because a flag does not take any arguments, the callback function is called with a null pointer for arg.

PARAMETER(s, l, p)

This macro creates an option which requires a parameter. p must be a char * lvalue which will be set to the encountered value.

PARAMETER_CALLBACK(s, l, c)

This macro creates a parameter option with a callback. Instead of storing the value into a variable, the callback function c is called with the encountered value for arg.

PARAMETER_DEFAULT(s, l, p, v)

Like PARAMETER, but if the value is ommitted on the command line, p will be set to v.

PARAMETER_DEFAULT_CALLBACK(s, l, c, v)

Like PARAMETER_CALLBACK, but if the value is ommitted on the command line, the callback function c is called with v for arg.