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 usually
introduced by
--
when both
letters
and
words
are not
NULL,
otherwise
-
or
--
can be used.
The set of characters that can introduce options are the ones mentioned in the string
optstr,
which by default is
"-+",
so
+
and
++
are normally also allowed.
getopt
always stores the character that introduced the option in
optchar,
so tests like
opt.optchar == '+'
let option handling code adjust its behavior based on the character that
introduced the option.
The special option
--
is always recognized (i.e., it is not affected by
optstr),
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 also be separated from an option letter or word
by white space (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
|
|
