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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | ATTRIBUTES | CONFORMING TO | BUGS | EXAMPLES | SEE ALSO | COLOPHON |
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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():
Since glibc 2.19:
_DEFAULT_SOURCE
Glibc 2.19 and earlier:
_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).
For an explanation of the terms used in this section, see
attributes(7).
┌──────────┬───────────────┬────────────────┐
│Interface │ Attribute │ Value │
├──────────┼───────────────┼────────────────┤
│rpmatch() │ Thread safety │ MT-Safe locale │
└──────────┴───────────────┴────────────────┘
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 5.10 of the Linux man-pages project.
A description of the project, information about reporting bugs,
and the latest version of this page, can be found at
https://www.kernel.org/doc/man-pages/.
GNU 2020-06-09 RPMATCH(3)
Pages that refer to this page: setlocale(3), locale(7)
Copyright and license for this manual page
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