wnargp(3)

NAME

wn_parse_args, wn_push_parse_args_error_print,

wn_pop_parse_args_error_print - parse UNIX-style arguments

SYNOPSIS

#include <wn/wnargp.h>
wn_parse_args(argc,argv,arg_format_array)
int argc;
char *argv[];
wn_arg_format arg_format_array[];
wn_push_parse_args_error_print(ppassed_print_error)
void (*ppassed_print_error)(/* string */);
wn_pop_parse_args_error_print()

DESCRIPTION

This package allows one to easily parse argc-argv argu

ments in the standard UNIX way.

wn_parse_args parses argv according to the format speci

fied in arg_format_array. argv has argc arguments. The follow

ing types of arguments are recognized:

1) Keyword boolean. The presence or absence of a flag

controls a boolean variable in your C program. A <flag> is any

string immediately preceded by a '-' character. Specify a key

word boolean by placing a WN_KEY_BOOL call in your format array.

Position in the argument list is ignored.

2) Keyword string. A keyword string is a flag followed

by a string argument. If this argument is present, a variable in

your program is set to the value of the string argument. Posi

tion in the argument list is ignored. Specify a keyword string

by placing a WN_KEY_STRING call in your format array.

3) Positional string. A positional string is a string

argment with no associated flag. Its meaning depends on its po

sition relative to other positional strings. If this argument is

present, a variable in your program is set to the value of the

string argument. Specify a keyword boolean flag by placing a

WN_POS_STRING

WN_POS_STRING

der the positional string arguments are expected in the argument
list.
Key strings or positional strings may be optional or re

quired. Not including a required argument is an argument syntax

error.

All argument syntax errors (that is, the user types in the

wrong arguments to a command) cause a standard UNIX command usage

message to be printed. By default, the message goes to standard

error and the program exits. This may be changed by pushing a

different print routine using wn_push_parse_args_error_print and

wn_pop_parse_args_error_print.

EXAMPLES

Consider the code fragment below.
#include <wn/wnargp.h>

bool recover;
char *control_filename,*error_filename,*in_file

name,*out_filename;

main(argc,argv)
int argc;
char *argv[];
{
static wn_arg_format arg_format_array[] = {
WN_KEY_BOOL(&recover,>r"),
WN_KEY_STRING(&control_filename,>g","control_file",WN_RE

QUIRED),
WN_KEY_STRING(&error_filename,>log","error_file",WN_OP

TIONAL),
WN_POS_STRING(&in_filename,>in_file",WN_REQUIRED),
WN_POS_STRING(&out_filename,>out_file",WN_OPTIONAL),
WN_ARG_TERMINATE
};

error_filename = <dastoinf.log>; /* defaults */
inf_filename = <net.inf>;

wn_parse_args(argc,argv,arg_format_array);

}
Typing bad arguments produces the message:

usage: command [-r] -g control_file [-log error_file]

in_file [out_file]

SEE ALSO

wnargv

AUTHOR

Will Naylor

WNLIB August 23, 1998

WNARGP(3)