rpmatch(3) — Linux manual page


rpmatch(3)              Library Functions Manual              rpmatch(3)

NAME         top

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

LIBRARY         top

       Standard C library (libc, -lc)

SYNOPSIS         top

       #include <stdlib.h>

       int rpmatch(const char *response);

   Feature Test Macro Requirements for glibc (see

           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 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).

ATTRIBUTES         top

       For an explanation of the terms used in this section, see
       │ Interface                    Attribute     Value          │
       │ rpmatch()                    │ Thread safety │ MT-Safe locale │

STANDARDS         top


HISTORY         top

       GNU, FreeBSD, AIX.

BUGS         top

       The YESEXPR and NOEXPR of some locales (including "C") only
       inspect the first character of the response.  This can mean that
       "yno" et al. resolve to 1.  This is an unfortunate historical
       side-effect which should be fixed in time with proper
       localisation, and should not deter from rpmatch() being the
       proper way to distinguish between binary answers.

EXAMPLES         top

       The following program displays the results when rpmatch() is
       applied to the string given in the program's command-line

       #define _DEFAULT_SOURCE
       #include <locale.h>
       #include <stdio.h>
       #include <stdlib.h>
       #include <string.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

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Linux man-pages 6.9.1          2024-06-15                     rpmatch(3)

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