This structure specifies how to parse a given set of options and arguments, perhaps in conjunction with other argp parsers. It has the following fields:

const struct argp_option *options

A pointer to a vector of argp_option structures specifying which options this argp parser understands; it may be zero if there are no options at all. See Argp Option Vectors.

argp_parser_t parser

A pointer to a function that defines actions for this parser; it is called for each option parsed, and at other well-defined points in the parsing process. A value of zero is the same as a pointer to a function that always returns ARGP_ERR_UNKNOWN. See Argp Parser Functions.

const char *args_doc

If non-zero, a string describing what non-option arguments are called by this parser. This is only used to print the `Usage:' message. If it contains newlines, the strings separated by them are considered alternative usage patterns and printed on separate lines. Lines after the first are prefixed by ` or: ' instead of `Usage:'.

const char *doc

If non-zero, a string containing extra text to be printed before and after the options in a long help message, with the two sections separated by a vertical tab ('\v', '\013') character. By convention, the documentation before the options is just a short string explaining what the program does. Documentation printed after the options describe behavior in more detail.

const struct argp_child *children

A pointer to a vector of argp_children structures. This pointer specifies which additional argp parsers should be combined with this one. See Argp Children.

char *(*help_filter)(int key, const char *text, void *input)

If non-zero, a pointer to a function that filters the output of help messages. See Argp Help Filtering.

const char *argp_domain

If non-zero, the strings used in the argp library are translated using the domain described by this string. If zero, the current default domain is used.