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RPMATCH(3) Linux Programmer's Manual RPMATCH(3)
rpmatch - determine if the answer to a question is affirmative or negative
#include <stdlib.h>
int rpmatch(const char *response);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
rpmatch(): _SVID_SOURCE
rpmatch() handles a user response to yes or no questions, with support for
internationalization.
response should be a null-terminated string containing a user-supplied
response, perhaps obtained with fgets(3) or getline(3).
The user's language preference is taken into account per the environment
variables LANG, LC_MESSAGES, and LC_ALL, if the program has called
setlocale(3) to effect their changes.
Regardless of the locale, responses matching ^[Yy] are always accepted as
affirmative, and those matching ^[Nn] are always accepted as negative.
After examining response, rpmatch() returns 0 for a recognized negative
response ("no"), 1 for a recognized positive response ("yes"), and -1 when the
value of response is unrecognized.
A return value of -1 may indicate either an invalid input, or some other
error. It is incorrect to only test if the return value is nonzero.
rpmatch() can fail for any of the reasons that regcomp(3) or regexec(3) can
fail; the cause of the error is not available from errno or anywhere else, but
indicates a failure of the regex engine (but this case is indistinguishable
from that of an unrecognized value of response).
rpmatch() is not required by any standard, but is available on a few other
systems.
The rpmatch() implementation looks at only the first character of response.
As a consequence, "nyes" returns 0, and "ynever; not in a million years"
returns 1. It would be preferable to accept input strings much more strictly,
for example (using the extended regular expression notation described in
regex(7)): ^([yY]|yes|YES)$ and ^([nN]|no|NO)$.
The following program displays the results when rpmatch() is applied to the
string given in the program's command-line argument.
#define _SVID_SOURCE
#include <locale.h>
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
int
main(int argc, char *argv[])
{
if (argc != 2 || strcmp(argv[1], "--help") == 0) {
fprintf(stderr, "%s response\n", argv[0]);
exit(EXIT_FAILURE);
}
setlocale(LC_ALL, "");
printf("rpmatch() returns: %d\n", rpmatch(argv[1]));
exit(EXIT_SUCCESS);
}
fgets(3), getline(3), nl_langinfo(3), regcomp(3), setlocale(3)
This page is part of release 3.32 of the Linux man-pages project. A
description of the project, and information about reporting bugs, can be found
at http://www.kernel.org/doc/man-pages/.
GNU 2007-07-26 RPMATCH(3)
HTML rendering created 2010-12-03 by Michael Kerrisk, author of The Linux Programming Interface