Returns an
int
that represents the next option in
args
that is matched by
letters
or
words,
-1
when no more options are left, and
?
if there was an error.
letters
describe single character options.
words,
which must be an array of strings, describe long options that are
introduced by
--
when both
letters
and
words
are not
NULL,
otherwise
-
or
--
can be used.
The special option
--
is always recognized, skipped, and forces
getopt
to return
-1,
which means it can be used to separate options from non-option arguments.
An option letter or long option name that is followed by a single colon in
letters
or
words
requires an argument, two colons means the argument is optional,
and no colon means the option does not take an argument.
An option's argument is always stored in
optarg,
which will be
NULL
when no argument was found.
Long options in
args
use an equal sign to separate an option name from its argument.
A required argument can be separated from an option letter or word
(i.e., it can follow the option in the
args
array),
but an optional argument can not.
When
getopt
recognizes a long option that is described by an entry in
words
it saves the name of that option in
optword,
otherwise
optword
will be
NULL.
By default
getopt
returns
-
when a long option is recognized, however an entry in
words
that contains
=
tells
getopt
to return the single character that follows the equal sign.
| |
| Example: |
Put the program,
import yoix.*.*;
Option option;
int ch;
while ((ch = option.getopt(global.argv, "a:bcx:y:")) != -1) {
switch (ch) {
case 'a':
case 'x':
case 'y':
printf("ch=%c, optarg=%s\n", ch, option.optarg);
break;
case 'b':
case 'c':
printf("ch=%c\n", ch);
break;
case '?':
fprintf(stderr, "Error: %s\n", option.opterror);
break;
}
}
printf("Remaining arguments: %O\n", global.argv + option.optind);
in a file named
getopt.yx,
run the interpreter by typing,
yoix getopt.yx -x12.3 -bc arg1 arg2
and
ch=x, optarg=12.3
ch=b
ch=c
Remaining arguments: Array[5:3]
^"getopt.yx"
^"-x12.3"
^"-bc"
>^"arg1"
^"arg2"
prints on standard output. Change the program to
import yoix.*.*;
Option option;
int ch;
Array words = {
"help", // no arg, return '-'
"info", // no arg, return '-'
"test:", // required arg, return '-'
"run=r::", // optional arg, return 'r'
};
while ((ch = option.getopt(global.argv, words)) != -1) {
switch (ch) {
case 'r':
printf("word=%s, arg=%O\n", option.optword,
option.optarg);
break;
case '-':
switch (option.optword) {
case "help":
printf("word=%s, arg=%O\n", option.optword,
option.optarg);
break;
case "info":
printf("word=%s, arg=%O\n", option.optword,
option.optarg);
break;
default:
printf("word=%s, arg=%O\n", option.optword,
option.optarg);
break;
}
break;
case '?':
fprintf(stderr, "Error: %s\n", option.opterror);
break;
}
}
printf("Remaining arguments: %O\n", global.argv + option.optind);
and type
yoix getopt.yx --help -info --test=12 arg1 arg2
and
word=help, arg=NULL:OBJECT
word=info, arg=NULL:OBJECT
word=test, arg=12
Remaining arguments: Array[6:4]
^"/tmp/xxx"
^"--help"
^"-info"
^"--test=12"
>^"arg1"
^"arg2"
prints on standard output.
Notice that we could use
-
or
--
to introduce the long options because there were no single character options for
getopt
to recognize.
| | |
| Return: |
int
| | |
| See Also: |
Option
|
|
