1NL_LANGINFO(3P) POSIX Programmer's Manual NL_LANGINFO(3P)
2
6 This manual page is part of the POSIX Programmer's Manual. The Linux
7 implementation of this interface may differ (consult the corresponding
8 Linux manual page for details of Linux behavior), or the interface may
9 not be implemented on Linux.
10
12 nl_langinfo, nl_langinfo_l — language information
13
15 #include <langinfo.h>
16 char *nl_langinfo(nl_item item);
18 char *nl_langinfo_l(nl_item item, locale_t locale);
19
21 The nl_langinfo() and nl_langinfo_l() functions shall return a pointer
22 to a string containing information relevant to the particular language
23 or cultural area defined in the current locale, or in the locale repre‐
24 sented by locale, respectively (see <langinfo.h>). The manifest con‐
25 stant names and values of item are defined in <langinfo.h>. For exam‐
26 ple:
27 nl_langinfo(ABDAY_1)
30 would return a pointer to the string "Dom" if the identified language
32 was Portuguese, and "Sun" if the identified language was English.
33 nl_langinfo_l(ABDAY_1, loc)
36 would return a pointer to the string "Dom" if the identified language
38 of the locale represented by loc was Portuguese, and "Sun" if the iden‐
39 tified language of the locale represented by loc was English.
40 The nl_langinfo() function need not be thread-safe.
42 The behavior is undefined if the locale argument to nl_langinfo_l() is
44 the special locale object LC_GLOBAL_LOCALE or is not a valid locale
45 object handle.
46
48 In a locale where langinfo data is not defined, these functions shall
49 return a pointer to the corresponding string in the POSIX locale. In
50 all locales, these functions shall return a pointer to an empty string
51 if item contains an invalid setting.
52 The application shall not modify the string returned. The pointer
54 returned by nl_langinfo() might be invalidated or the string content
55 might be overwritten by a subsequent call to nl_langinfo() in any
56 thread or to nl_langinfo_l() in the same thread or the initial thread,
57 by subsequent calls to setlocale() with a category corresponding to the
58 category of item (see <langinfo.h>) or the category LC_ALL, or by sub‐
59 sequent calls to uselocale() which change the category corresponding to
60 the category of item. The pointer returned by nl_langinfo_l() might be
61 invalidated or the string content might be overwritten by a subsequent
62 call to nl_langinfo_l() in the same thread or to nl_langinfo() in any
63 thread, or by subsequent calls to freelocale() or newlocale() which
64 free or modify the locale object that was passed to nl_langinfo_l().
65 The returned pointer and the string content might also be invalidated
66 if the calling thread is terminated.
67
69 No errors are defined.
70 The following sections are informative.
72
74 Getting Date and Time Formatting Information
75 The following example returns a pointer to a string containing date and
76 time formatting information, as defined in the LC_TIME category of the
77 current locale.
78 #include <time.h>
81 #include <langinfo.h>
82 ...
83 strftime(datestring, sizeof(datestring), nl_langinfo(D_T_FMT), tm);
84 ...
85
87 The array pointed to by the return value should not be modified by the
88 program, but may be modified by further calls to these functions.
89
91 The possible interactions between internal data used by nl_langinfo()
92 and nl_langinfo_l() are complicated by the fact that nl_langinfo_l()
93 must be thread-safe but nl_langinfo() need not be. The various imple‐
94 mentation choices are:
95 1. nl_langinfo_l() and nl_langinfo() use separate buffers, or at least
97 one of them does not use an internal string buffer. In this case
98 there are no interactions.
99 2. nl_langinfo_l() and nl_langinfo() share an internal per-thread buf‐
101 fer. There can be interactions, but only in the same thread.
102 3. nl_langinfo_l() uses an internal per-thread buffer, and nl_lang‐
104 info() uses (in all threads) the same buffer that nl_langinfo_l()
105 uses in the initial thread. There can be interactions, but only
106 when nl_langinfo_l() is called in the initial thread.
107
109 None.
110
112 setlocale(), uselocale()
113 The Base Definitions volume of POSIX.1‐2017, Chapter 7, Locale, <lang‐
115 info.h>, <locale.h>, <nl_types.h>
116
118 Portions of this text are reprinted and reproduced in electronic form
119 from IEEE Std 1003.1-2017, Standard for Information Technology -- Por‐
120 table Operating System Interface (POSIX), The Open Group Base Specifi‐
121 cations Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of
122 Electrical and Electronics Engineers, Inc and The Open Group. In the
123 event of any discrepancy between this version and the original IEEE and
124 The Open Group Standard, the original IEEE and The Open Group Standard
125 is the referee document. The original Standard can be obtained online
126 at http://www.opengroup.org/unix/online.html .
127 Any typographical or formatting errors that appear in this page are
129 most likely to have been introduced during the conversion of the source
130 files to man page format. To report such errors, see https://www.ker‐
131 nel.org/doc/man-pages/reporting_bugs.html .
132IEEE/The Open Group 2017 NL_LANGINFO(3P)