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():
17           Since glibc 2.19:
18               _DEFAULT_SOURCE
19           Glibc 2.19 and earlier:
20               _SVID_SOURCE
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DESCRIPTION

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

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

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

53       For  an  explanation  of  the  terms  used  in  this  section,  see at‐
54       tributes(7).
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56       ┌──────────┬───────────────┬────────────────┐
57       │Interface │ Attribute     │ Value          │
58       ├──────────┼───────────────┼────────────────┤
59       │rpmatch() │ Thread safety │ MT-Safe locale │
60       └──────────┴───────────────┴────────────────┘
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CONFORMING TO

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

67       The  rpmatch()  implementation looks at only the first character of re‐
68       sponse.  As a consequence, "nyes" returns 0, and "ynever; not in a mil‐
69       lion  years" returns 1.  It would be preferable to accept input strings
70       much more strictly, for example (using the extended regular  expression
71       notation described in regex(7)): ^([yY]|yes|YES)$ and ^([nN]|no|NO)$.
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EXAMPLES

74       The following program displays the results when rpmatch() is applied to
75       the string given in the program's command-line argument.
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77       #define _SVID_SOURCE
78       #include <locale.h>
79       #include <stdlib.h>
80       #include <string.h>
81       #include <stdio.h>
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83       int
84       main(int argc, char *argv[])
85       {
86           if (argc != 2 || strcmp(argv[1], "--help") == 0) {
87               fprintf(stderr, "%s response\n", argv[0]);
88               exit(EXIT_FAILURE);
89           }
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91           setlocale(LC_ALL, "");
92           printf("rpmatch() returns: %d\n", rpmatch(argv[1]));
93           exit(EXIT_SUCCESS);
94       }
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COLOPHON

100       This page is part of release 5.10 of the Linux  man-pages  project.   A
101       description  of  the project, information about reporting bugs, and the
102       latest    version    of    this    page,    can     be     found     at
103       https://www.kernel.org/doc/man-pages/.
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107GNU                               2020-06-09                        RPMATCH(3)