1LOCALE(7) Linux Programmer's Manual LOCALE(7)
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6 locale - Description of multi-language support
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9 #include <locale.h>
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12 A locale is a set of language and cultural rules. These cover aspects
13 such as language for messages, different character sets, lexicographic
14 conventions, etc. A program needs to be able to determine its locale
15 and act accordingly to be portable to different cultures.
16 The header <locale.h> declares data types, functions and macros which
18 are useful in this task.
19 The functions it declares are setlocale(3) to set the current locale,
21 and localeconv(3) to get information about number formatting.
22 There are different categories for local information a program might
24 need; they are declared as macros. Using them as the first argument to
25 the setlocale(3) function, it is possible to set one of these to the
26 desired locale:
27 LC_COLLATE
29 This is used to change the behavior of the functions strcoll(3)
30 and strxfrm(3), which are used to compare strings in the local
31 alphabet. For example, the German sharp s is sorted as "ss".
32 LC_CTYPE
34 This changes the behavior of the character handling and classi‐
35 fication functions, such as isupper(3) and toupper(3), and the
36 multi-byte character functions such as mblen(3) or wctomb(3).
37 LC_MONETARY
39 changes the information returned by localeconv(3) which
40 describes the way numbers are usually printed, with details such
41 as decimal point versus decimal comma. This information is
42 internally used by the function strfmon(3).
43 LC_MESSAGES
45 changes the language messages are displayed in and what an
46 affirmative or negative answer looks like. The GNU C-library
47 contains the gettext(3), ngettext(3), and rpmatch(3) functions
48 to ease the use of these information. The GNU gettext family of
49 functions also obey the environment variable LANGUAGE (contain‐
50 ing a colon-separated list of locales) if the category is set to
51 a valid locale other than "C".
52 LC_NUMERIC
54 changes the information used by the printf(3) and scanf(3) fam‐
55 ily of functions, when they are advised to use the locale-set‐
56 tings. This information can also be read with the localeconv(3)
57 function.
58 LC_TIME
60 changes the behavior of the strftime(3) function to display the
61 current time in a locally acceptable form; for example, most of
62 Europe uses a 24-hour clock versus the 12-hour clock used in the
63 United States.
64 LC_ALL All of the above.
66 If the second argument to setlocale(3) is empty string, "", for the
68 default locale, it is determined using the following steps:
69 1. If there is a non-null environment variable LC_ALL, the value of
71 LC_ALL is used.
72 2. If an environment variable with the same name as one of the cat‐
74 egories above exists and is non-null, its value is used for that
75 category.
76 3. If there is a non-null environment variable LANG, the value of
78 LANG is used.
79 Values about local numeric formatting is made available in a struct
81 lconv returned by the localeconv(3) function, which has the following
82 declaration:
83 struct lconv {
85 /* Numeric (non-monetary) information */
87 char *decimal_point; /* Radix character */
89 char *thousands_sep; /* Separator for digit groups to left
90 of radix character */
91 char *grouping; /* Each element is the number of digits in a
92 group; elements with higher indices are
93 further left. An element with value CHAR_MAX
94 means that no further grouping is done. An
95 element with value 0 means that the previous
96 element is used for all groups further left. */
97 /* Remaining fields are for monetary information */
99 char *int_curr_symbol; /* First three chars are a currency symbol
101 from ISO 4217. Fourth char is the
102 separator. Fifth char is '\0'. */
103 char *currency_symbol; /* Local currency symbol */
104 char *mon_decimal_point; /* Radix character */
105 char *mon_thousands_sep; /* Like thousands_sep above */
106 char *mon_grouping; /* Like grouping above */
107 char *positive_sign; /* Sign for positive values */
108 char *negative_sign; /* Sign for negative values */
109 char int_frac_digits; /* International fractional digits */
110 char frac_digits; /* Local fractional digits */
111 char p_cs_precedes; /* 1 if currency_symbol precedes a
112 positive value, 0 if succeeds */
113 char p_sep_by_space; /* 1 if a space separates currency_symbol
114 from a positive value */
115 char n_cs_precedes; /* 1 if currency_symbol precedes a
116 negative value, 0 if succeeds */
117 char n_sep_by_space; /* 1 if a space separates currency_symbol
118 from a negative value */
119 /* Positive and negative sign positions:
120 0 Parentheses surround the quantity and currency_symbol.
121 1 The sign string precedes the quantity and currency_symbol.
122 2 The sign string succeeds the quantity and currency_symbol.
123 3 The sign string immediately precedes the currency_symbol.
124 4 The sign string immediately succeeds the currency_symbol. */
125 char p_sign_posn;
126 char n_sign_posn;
127 };
128
130 POSIX.1-2001.
131 The GNU gettext functions are specified in LI18NUX2000.
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135 locale(1), localedef(1), gettext(3), localeconv(3), ngettext(3),
136 nl_langinfo(3), rpmatch(3), setlocale(3), strcoll(3), strfmon(3), strf‐
137 time(3), strxfrm(3)
138
140 This page is part of release 3.22 of the Linux man-pages project. A
141 description of the project, and information about reporting bugs, can
142 be found at http://www.kernel.org/doc/man-pages/.
143Linux 2008-12-05 LOCALE(7)