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

NAME
       rpmatch - determine if the answer to a question is affirmative or nega-
       tive
SYNOPSIS
       #include <stdlib.h>
       int rpmatch(const char *response);
   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
       rpmatch(): _SVID_SOURCE
DESCRIPTION
       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  environ-
       ment 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 nega-
       tive.
RETURN VALUE
       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
       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 any-
       where else, but indicates a failure of the regex engine (but this  case
       is indistinguishable from that of an unrecognized value of response).
CONFORMING TO
       rpmatch()  is  not  required by any standard, but is available on a few
       other systems.
BUGS
       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)$.
EXAMPLE
       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);
       }
SEE ALSO
       fgets(3), getline(3), nl_langinfo(3), regcomp(3), setlocale(3)
COLOPHON
       This page is part of release 3.53 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)