wn_parse_args, wn_push_parse_args_error_print, wn_pop_parse_args_error_print - parse UNIX-style arguments

#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()

This package allows one to easily parse argc-argv arguments in the standard UNIX way.

wn_parse_args parses argv according to the format specified in arg_format_array. argv has argc arguments. The following 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 keyword 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. Position 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 position 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 call in your format array. The order in which WN_POS_STRING calls appear in the format array determine the order the positional string arguments are expected in the argument list.

Key strings or positional strings may be optional or required. 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.

Consider the code fragment below.

#include <wn/wnargp.h>

bool recover; char *control_filename,*error_filename,*in_filename,*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_REQUIRED), WN_KEY_STRING(&error_filename,>log","error_file",WN_OPTIONAL), 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]

wnargv

Will Naylor