1RPMATCH(3) Linux Programmer's Manual RPMATCH(3)
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6 rpmatch - determine if the answer to a question is affirmative or nega‐
7 tive
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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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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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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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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 non-
41 zero.
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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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49 rpmatch() is not required by any standard, but is available on a few
50 other systems.
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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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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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84 fgets(3), getline(3), nl_langinfo(3), regcomp(3), setlocale(3)
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87 This page is part of release 3.22 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)