NAME
Cgetopt_long - get long options from command line argument list
SYNOPSIS
#include <Cgetopt.h>
int Cgetopt (int argc, char **argv, char *optstring)
int Cgetopt_long (int argc, char **argv, char *optstring, Coptions_t
*long_options, int *index)
DESCRIPTION
The Cgetopt function incrementally parses a command line argument list
argv and returns the next known option character. An option character
is known if it has been specified in the string of accepted option
characters optstring.
The Cgetopt_long function is similar to Cgetopt but it accepts options
in two forms: words and characters. The Cgetopt_long function provides
a superset of the functionality of Cgetopt. The additional
functionality is described in the section CGETOPT_LONG.
The option string optstring may contain the following elements:
individual characters, and characters followed by a colon to indicate
an option argument is to follow. For example, an option string x
recognizes an option x , and an option string x: recognizes an option x
taking an argument. It does not matter to Cgetopt if a following
argument has leading white space.
On return from Cgetopt, Coptarg points to an option argument, if it is
anticipated, and the variable Coptind contains the index to the next
argv argument for a subsequent call to Cgetopt. The variable Coptopt
saves the last known option character returned by Cgetopt.
The variables Copterr and Coptind are both initialized to 1. The
Coptind variable may be set to another value before a set of calls to
Cgetopt in order to skip over more or less argv entries.
In order to use Cgetopt to evaluate multiple sets of arguments, or to
evaluate a single set of arguments multiple times, the variable
Coptreset must be set to 1 before the second and each additional set of
calls to Cgetopt and the variable Coptind must be reinitialized.
The Cgetopt function returns -1 when the argument list is exhausted, or
a non-recognized option is encountered. The interpretation of options
in the argument list may be cancelled by the option -- (double dash)
which causes Cgetopt to signal the end of argument processing and
returns -1. When all options have been processed (i.e., up to the first
non-option argument), Cgetopt returns -1.
Cgetopt_long can be used in two ways. In the first way, every long
option understood by the program has a coresponding short option, and
the option structure is only used to translate from long option to
short options. When used in this fashion, Cgetopt_long behaves
identically to Cgetopt. This is good way to add long option processing
to an existing program with the minimum of rewriting.
In the second mechanism, a long option set a flag in the Coptions_t
structure passed, or will store a pointer to the command line argument
in the Coptions_t structure passed to it for options that take
arguments. Additionally, the long option’s argument may be specified as
a single argument with an equal sign, e.g myprogram
--myoption=somevalue
When a long option is processed the call to Cgetopt_long will return 0.
For this reason, long option processing without shortcuts are not
backwards compatible with Cgetopt.
It is possible to combine these methods, providing for long options
processing with short option equivalents for some options. Less
frequently used options would be processed as long options only.
USAGE OF CGETOPT_LONG
The Cgetopt_long call requires a structure to be initialized describing
the long options. The structure is:
Coptions_t {
char *name;
int has_arg;
int *flag;
int val;
};
The name field should contain the option name without the leading
double dash.
The has_arg field should be one of: NO_ARGUMENT if no argument to the
option is expected, REQUIRED_ARGUMENT if an argument to the option is
required or OPTIONAL_ARGUMENT if an argument to the option may be
presented.
If flag is non-NULL, then the integer pointed to by it will set to the
value in the val field. If the flag field is NULL, then the val field
will be returned. Setting flag to NULL and setting val to the
corresponding short option will make this function act just like
Cgetopt.
DIAGNOSTICS
If the Cgetopt function encounters a character not found in the string
optstring or detects a missing option argument it writes an error
message to stderr and returns ?. Setting Copterr to a zero will
disable these error messages. If optstring has a leading : then a
missing option argument causes a : to be returned in addition to
suppressing any error messages.
Option arguments are allowed to begin with - ; this is reasonable but
reduces the amount of error checking possible.
CGETOPT_LONG EXTENSIONS
The Coptreset variable was added to make it possible to call the
Cgetopt function multiple times. This is an extension to the -p1003.2
specification.
EXAMPLE
#include <Cgetopt.h>
int bflag, ch, fd;
Coptind = 1; /* Required */
Copterr = 1; /* Some stderr output if you want */
bflag = 0;
while ((ch = Cgetopt(argc, argv, "bf:")) != -1)
switch(ch) {
case ’b’:
bflag = 1;
break;
case ’f’:
if ((fd = open(Coptarg, O_RDONLY, 0)) < 0) {
(void)fprintf(stderr,
"myname: %s: %s\n", Coptarg, strerror(errno));
exit(1);
}
break;
case ’?’:
default:
usage();
}
argc -= Coptind;
argv += Coptind;
LONG EXAMPLE
#include <Cgetopt.h>
int bflag, ch, fd;
int daggerset;
/* options descriptor */
Coptions_t longopts[] =
{
{"buffy", NO_ARGUMENT, NULL, ’b’},
{"floride", REQUIRED_ARGUMENT, NULL, ’f’},
{"daggerset", NO_ARGUMENT, &daggerset, 1},
{NULL, 0, NULL, 0}
};
Coptind = 1; /* Required */
Copterr = 1; /* Some stderr output if you want */
bflag = 0;
while ((ch = Cgetopt_long(argc, argv, "bf:", longopts, NULL)) != -1)
switch(ch) {
case ’b’:
bflag = 1;
break;
case ’f’:
if ((fd = open(Coptarg, O_RDONLY, 0)) < 0) {
(void)fprintf(stderr,
"myname: %s: %s\n", Coptarg, strerror(errno));
exit(1);
}
break;
case 0:
if(daggerset) {
fprintf(stderr,"Buffy will put use her dagger"
"to apply floride to dracula’s teeth");
}
break;
case ’?’:
default:
usage();
}
argc -= Coptind;
argv += Coptind;
HISTORY
The Cgetopt function appeared in BSD 4.3. The Cgetopt_long function
first appeared in GNU library. This implementation was imported to
NetBSD from a Kerberos distribution.
BUGS
The Cgetopt function was once specified to return EOF instead of -1.
This was changed by -p1003.2-92 to decouple Cgetopt from <stdio.h>.
A single dash - may be specified as an character in optstring, however
it should never have an argument associated with it. This allows
Cgetopt to be used with programs that expect - as an option flag. This
practice is wrong, and should not be used in any current development.
It is provided for backward compatibility only. By default, a single
dash causes Cgetopt to return -1. This is, we believe, compatible with
System V.
It is also possible to handle digits as option letters. This allows
Cgetopt to be used with programs that expect a number -3 as an option.
This practice is wrong, and should not be used in any current
development. It is provided for backward compatibility only. The
following code fragment works in most cases.
int length;
char *p;
Coptind = 1; /* Required */
Copterr = 1; /* Some stderr output if you want */
while ((c = Cgetopt(argc, argv, "0123456789")) != -1)
switch (c) {
case ’0’: case ’1’: case ’2’: case ’3’: case ’4’:
case ’5’: case ’6’: case ’7’: case ’8’: case ’9’:
p = argv[Coptind - 1];
if (p[0] == ’-’ && p[1] == ch && !p[2])
length = atoi(++p);
else
length = atoi(argv[Coptind] + 1);
break;
}
}
The OPTIONAL_ARGUMENT always eats the following argument unless the
argument is included via the --option=argument notation.
AUTHOR
Copyright (c) 1988, 1991, 1993 The Regents of the University of
California. All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are
met:
1. Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
3. All advertising materials mentioning features or use of this
software must display the following acknowledgement: This product
includes software developed by the University of California, Berkeley
and its contributors.
4. Neither the name of the University nor the names of its contributors
may be used to endorse or promote products derived from this software
without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ‘‘AS IS’’ AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS
BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
LCG $Date: 2010-04-05 09:51:26 +0200 (Mon, 05 Apr 2010CGETOPT_LONG(3)