rpmatch(3) — Linux manual page


RPMATCH(3)                Linux Programmer's Manual               RPMATCH(3)

NAME         top

       rpmatch  -  determine  if  the answer to a question is affirmative or

SYNOPSIS         top

       #include <stdlib.h>

       int rpmatch(const char *response);

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

           Since glibc 2.19:
           Glibc 2.19 and earlier:

DESCRIPTION         top

       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.

RETURN VALUE         top

       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.

ERRORS         top

       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

       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).

ATTRIBUTES         top

       For an explanation of the terms used in this section, see

       │Interface Attribute     Value          │
       │rpmatch() │ Thread safety │ MT-Safe locale │

CONFORMING TO         top

       rpmatch() is not required by any standard, but is available on a few
       other systems.

BUGS         top

       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

EXAMPLES         top

       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>

       main(int argc, char *argv[])
           if (argc != 2 || strcmp(argv[1], "--help") == 0) {
               fprintf(stderr, "%s response\n", argv[0]);

           setlocale(LC_ALL, "");
           printf("rpmatch() returns: %d\n", rpmatch(argv[1]));

SEE ALSO         top

       fgets(3), getline(3), nl_langinfo(3), regcomp(3), setlocale(3)

COLOPHON         top

       This page is part of release 5.08 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

GNU                              2020-06-09                       RPMATCH(3)

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