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



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

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 get-
       line(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
       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 anywhere 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 exam-
       ple (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 3.25 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)