rpmatch(3)

1RPMATCH(3)                 Linux Programmer's Manual                RPMATCH(3)
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NAME

6       rpmatch - determine if the answer to a question is affirmative or nega‐
7       tive
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SYNOPSIS

10       #include <stdlib.h>
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12       int rpmatch(const char *response);
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14   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
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16       rpmatch(): _SVID_SOURCE
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DESCRIPTION

19       rpmatch() handles a user response to yes or no questions, with  support
20       for internationalization.
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22       response  should be a null-terminated string containing a user-supplied
23       response, perhaps obtained with fgets(3) or getline(3).
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25       The user's language preference is taken into account per  the  environ‐
26       ment variables LANG, LC_MESSAGES, and LC_ALL, if the program has called
27       setlocale(3) to effect their changes.
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29       Regardless of the locale, responses matching ^[Yy] are always  accepted
30       as  affirmative,  and those matching ^[Nn] are always accepted as nega‐
31       tive.
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RETURN VALUE

34       After examining response, rpmatch() returns 0 for a recognized negative
35       response  ("no"),  1 for a recognized positive response ("yes"), and -1
36       when the value of response is unrecognized.
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ERRORS

39       A return value of -1 may indicate either  an  invalid  input,  or  some
40       other  error.   It  is  incorrect  to  only test if the return value is
41       nonzero.
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43       rpmatch() can fail for any of the reasons that regcomp(3) or regexec(3)
44       can  fail;  the  cause of the error is not available from errno or any‐
45       where else, but indicates a failure of the regex engine (but this  case
46       is indistinguishable from that of an unrecognized value of response).
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CONFORMING TO

49       rpmatch()  is  not  required by any standard, but is available on a few
50       other systems.
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BUGS

53       The rpmatch() implementation looks  at  only  the  first  character  of
54       response.   As  a  consequence, "nyes" returns 0, and "ynever; not in a
55       million years" returns 1.  It  would  be  preferable  to  accept  input
56       strings  much  more  strictly,  for example (using the extended regular
57       expression  notation  described  in  regex(7)):  ^([yY]|yes|YES)$   and
58       ^([nN]|no|NO)$.
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EXAMPLE

61       The following program displays the results when rpmatch() is applied to
62       the string given in the program's command-line argument.
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64       #define _SVID_SOURCE
65       #include <locale.h>
66       #include <stdlib.h>
67       #include <string.h>
68       #include <stdio.h>
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70       int
71       main(int argc, char *argv[])
72       {
73           if (argc != 2 || strcmp(argv[1], "--help") == 0) {
74               fprintf(stderr, "%s response\n", argv[0]);
75               exit(EXIT_FAILURE);
76           }
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78           setlocale(LC_ALL, "");
79           printf("rpmatch() returns: %d\n", rpmatch(argv[1]));
80           exit(EXIT_SUCCESS);
81       }
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COLOPHON

87       This page is part of release 3.25 of the Linux  man-pages  project.   A
88       description  of  the project, and information about reporting bugs, can
89       be found at http://www.kernel.org/doc/man-pages/.
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93GNU                               2007-07-26                        RPMATCH(3)