1 .\" Copyright (C) 2006 Justin Pryzby <pryzbyj@justinpryzby.com>
3 .\" %%%LICENSE_START(PERMISSIVE_MISC)
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5 .\" a copy of this software and associated documentation files (the
6 .\" "Software"), to deal in the Software without restriction, including
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9 .\" permit persons to whom the Software is furnished to do so, subject to
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15 .\" THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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25 .\" glibc manual and source
27 .\" 2006-05-19, mtk, various edits and example program
29 .TH RPMATCH 3 2007-07-26 "GNU" "Linux Programmer's Manual"
31 rpmatch \- determine if the answer to a question is affirmative or negative
34 .B #include <stdlib.h>
36 .BI "int rpmatch(const char *" response );
40 Feature Test Macro Requirements for glibc (see
41 .BR feature_test_macros (7)):
48 handles a user response to yes or no questions, with
49 support for internationalization.
51 \fIresponse\fP should be a null-terminated string containing a
52 user-supplied response, perhaps obtained with
57 The user's language preference is taken into account per the
58 environment variables \fBLANG\fP, \fBLC_MESSAGES\fP, and \fBLC_ALL\fP,
59 if the program has called
61 to effect their changes.
63 Regardless of the locale, responses matching \fB^[Yy]\fP are always
64 accepted as affirmative, and those matching \fB^[Nn]\fP are always
70 returns 0 for a recognized negative response ("no"), 1
71 for a recognized positive response ("yes"), and \-1 when the value
72 of \fIresponse\fP is unrecognized.
74 A return value of \-1 may indicate either an invalid input, or some
76 It is incorrect to only test if the return value is nonzero.
79 can fail for any of the reasons that
83 can fail; the cause of the error
84 is not available from \fIerrno\fP or anywhere else, but indicates a
85 failure of the regex engine (but this case is indistinguishable from
86 that of an unrecognized value of \fIresponse\fP).
89 is not required by any standard, but
90 is available on a few other systems.
91 .\" It is available on at least AIX 5.1 and FreeBSD 6.0.
95 implementation looks at only the first character
97 As a consequence, "nyes" returns 0, and
98 "ynever; not in a million years" returns 1.
99 It would be preferable to accept input strings much more
100 strictly, for example (using the extended regular
101 expression notation described in
103 \fB^([yY]|yes|YES)$\fP and \fB^([nN]|no|NO)$\fP.
105 The following program displays the results when
107 is applied to the string given in the program's command-line argument.
117 main(int argc, char *argv[])
119 if (argc != 2 || strcmp(argv[1], "\-\-help") == 0) {
120 fprintf(stderr, "%s response\\n", argv[0]);
124 setlocale(LC_ALL, "");
125 printf("rpmatch() returns: %d\\n", rpmatch(argv[1]));