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():
	   Since glibc 2.19:
	       _DEFAULT_SOURCE
	   Glibc 2.19 and earlier:
	       _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 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 neg-
       ative.

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).

ATTRIBUTES

       For an explanation of the terms used in this section, see attributes(7).

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

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 mil-
       lion years" returns 1.  It would be preferable to accept input strings much more strictly, for example (using the extended regular  expres-
       sion 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
", argv[0]);
	       exit(EXIT_FAILURE);
	   }

	   setlocale(LC_ALL, "");
	   printf("rpmatch() returns: %d
", 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 4.15 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 https://www.kernel.org/doc/man-pages/.

GNU
								    2017-09-15								RPMATCH(3)