rpmatch(3) - Linux manual page (original) (raw)

rpmatch(3) Library Functions Manual rpmatch(3)

NAME top

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

LIBRARY top

   Standard C library (_libc_, _-lc_)

SYNOPSIS top

   **#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

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)](../man3/fgets.3.html) or [getline(3)](../man3/getline.3.html).

   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)](../man3/setlocale.3.html) 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)](../man3/regcomp.3.html) or
   [regexec(3)](../man3/regexec.3.html) can fail; the error is not available from _[errno](../man3/errno.3.html)_ 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
   [attributes(7)](../man7/attributes.7.html).
   ┌───────────────────────────────┬───────────────┬────────────────┐
   │ **Interface** │ **Attribute** │ **Value** │
   ├───────────────────────────────┼───────────────┼────────────────┤
   │ **rpmatch**()                     │ Thread safety │ MT-Safe locale │
   └───────────────────────────────┴───────────────┴────────────────┘

STANDARDS top

   None.

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
   argument.

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

COLOPHON top

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   man-pages@man7.org

Linux man-pages 6.10 2024-07-23 rpmatch(3)

Pages that refer to this page:setlocale(3), locale(7)