1LOCALE(7) Linux Programmer's Manual LOCALE(7)
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6 locale - description of multilanguage 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, and so on. A program needs to be able to determine its
15 locale 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 locale 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_ADDRESS (GNU extension, since glibc 2.2)
29 Change settings that describe the formats (e.g., postal
30 addresses) used to describe locations and geography-related
31 items. Applications that need this information can use nl_lang‐
32 info(3) to retrieve nonstandard elements, such as
33 _NL_ADDRESS_COUNTRY_NAME (country name, in the language of the
34 locale) and _NL_ADDRESS_LANG_NAME (language name, in the lan‐
35 guage of the locale), which return strings such as "Deutschland"
36 and "Deutsch" (for German-language locales). (Other element
37 names are listed in <langinfo.h>.)
38 LC_COLLATE
40 This category governs the collation rules used for sorting and
41 regular expressions, including character equivalence classes and
42 multicharacter collating elements. This locale category changes
43 the behavior of the functions strcoll(3) and strxfrm(3), which
44 are used to compare strings in the local alphabet. For example,
45 the German sharp s is sorted as "ss".
46 LC_CTYPE
48 This category determines the interpretation of byte sequences as
49 characters (e.g., single versus multibyte characters), character
50 classifications (e.g., alphabetic or digit), and the behavior of
51 character classes. On glibc systems, this category also deter‐
52 mines the character transliteration rules for iconv(1) and
53 iconv(3). It changes the behavior of the character handling and
54 classification functions, such as isupper(3) and toupper(3), and
55 the multibyte character functions such as mblen(3) or wctomb(3).
56 LC_IDENTIFICATION (GNU extension, since glibc 2.2)
58 Change settings that relate to the metadata for the locale.
59 Applications that need this information can use nl_langinfo(3)
60 to retrieve nonstandard elements, such as _NL_IDENTIFICA‐
61 TION_TITLE (title of this locale document) and _NL_IDENTIFICA‐
62 TION_TERRITORY (geographical territory to which this locale doc‐
63 ument applies), which might return strings such as "English
64 locale for the USA" and "USA". (Other element names are listed
65 in <langinfo.h>.)
66 LC_MONETARY
68 This category determines the formatting used for monetary-
69 related numeric values. This changes the information returned
70 by localeconv(3), which describes the way numbers are usually
71 printed, with details such as decimal point versus decimal
72 comma. This information is internally used by the function
73 strfmon(3).
74 LC_MESSAGES
76 This category affects the language in which messages are dis‐
77 played and what an affirmative or negative answer looks like.
78 The GNU C library contains the gettext(3), ngettext(3), and
79 rpmatch(3) functions to ease the use of this information. The
80 GNU gettext family of functions also obey the environment vari‐
81 able LANGUAGE (containing a colon-separated list of locales) if
82 the category is set to a valid locale other than "C". This cat‐
83 egory also affects the behavior of catopen(3).
84 LC_MEASUREMENT (GNU extension, since glibc 2.2)
86 Change the settings relating to the measurement system in the
87 locale (i.e., metric versus US customary units). Applications
88 can use nl_langinfo(3) to retrieve the nonstandard _NL_MEASURE‐
89 MENT_MEASUREMENT element, which returns a pointer to a character
90 that has the value 1 (metric) or 2 (US customary units).
91 LC_NAME (GNU extension, since glibc 2.2)
93 Change settings that describe the formats used to address per‐
94 sons. Applications that need this information can use nl_lang‐
95 info(3) to retrieve nonstandard elements, such as
96 _NL_NAME_NAME_MR (general salutation for men) and
97 _NL_NAME_NAME_MS (general salutation for women) elements, which
98 return strings such as "Herr" and "Frau" (for German-language
99 locales). (Other element names are listed in <langinfo.h>.)
100 LC_NUMERIC
102 This category determines the formatting rules used for nonmone‐
103 tary numeric values—for example, the thousands separator and the
104 radix character (a period in most English-speaking countries,
105 but a comma in many other regions). It affects functions such
106 as printf(3), scanf(3), and strtod(3). This information can
107 also be read with the localeconv(3) function.
108 LC_PAPER (GNU extension, since glibc 2.2)
110 Change the settings relating to the dimensions of the standard
111 paper size (e.g., US letter versus A4). Applications that need
112 the dimensions can obtain them by using nl_langinfo(3) to
113 retrieve the nonstandard _NL_PAPER_WIDTH and _NL_PAPER_HEIGHT
114 elements, which return int values specifying the dimensions in
115 millimeters.
116 LC_TELEPHONE (GNU extension, since glibc 2.2)
118 Change settings that describe the formats to be used with tele‐
119 phone services. Applications that need this information can use
120 nl_langinfo(3) to retrieve nonstandard elements, such as
121 _NL_TELEPHONE_INT_PREFIX (international prefix used to call num‐
122 bers in this locale), which returns a string such as "49" (for
123 Germany). (Other element names are listed in <langinfo.h>.)
124 LC_TIME
126 This category governs the formatting used for date and time val‐
127 ues. For example, most of Europe uses a 24-hour clock versus
128 the 12-hour clock used in the United States. The setting of
129 this category affects the behavior of functions such as strf‐
130 time(3) and strptime(3).
131 LC_ALL All of the above.
133 If the second argument to setlocale(3) is an empty string, "", for the
135 default locale, it is determined using the following steps:
136 1. If there is a non-null environment variable LC_ALL, the value of
138 LC_ALL is used.
139 2. If an environment variable with the same name as one of the cate‐
141 gories above exists and is non-null, its value is used for that cat‐
142 egory.
143 3. If there is a non-null environment variable LANG, the value of LANG
145 is used.
146 Values about local numeric formatting is made available in a struct
148 lconv returned by the localeconv(3) function, which has the following
149 declaration:
150 struct lconv {
152 /* Numeric (nonmonetary) information */
154 char *decimal_point; /* Radix character */
156 char *thousands_sep; /* Separator for digit groups to left
157 of radix character */
158 char *grouping; /* Each element is the number of digits in
159 a group; elements with higher indices
160 are further left. An element with value
161 CHAR_MAX means that no further grouping
162 is done. An element with value 0 means
163 that the previous element is used for
164 all groups further left. */
165 /* Remaining fields are for monetary information */
167 char *int_curr_symbol; /* First three chars are a currency
169 symbol from ISO 4217. Fourth char
170 is the separator. Fifth char
171 is '\0'. */
172 char *currency_symbol; /* Local currency symbol */
173 char *mon_decimal_point; /* Radix character */
174 char *mon_thousands_sep; /* Like thousands_sep above */
175 char *mon_grouping; /* Like grouping above */
176 char *positive_sign; /* Sign for positive values */
177 char *negative_sign; /* Sign for negative values */
178 char int_frac_digits; /* International fractional digits */
179 char frac_digits; /* Local fractional digits */
180 char p_cs_precedes; /* 1 if currency_symbol precedes a
181 positive value, 0 if succeeds */
182 char p_sep_by_space; /* 1 if a space separates
183 currency_symbol from a positive
184 value */
185 char n_cs_precedes; /* 1 if currency_symbol precedes a
186 negative value, 0 if succeeds */
187 char n_sep_by_space; /* 1 if a space separates
188 currency_symbol from a negative
189 value */
190 /* Positive and negative sign positions:
191 0 Parentheses surround the quantity and currency_symbol.
192 1 The sign string precedes the quantity and currency_symbol.
193 2 The sign string succeeds the quantity and currency_symbol.
194 3 The sign string immediately precedes the currency_symbol.
195 4 The sign string immediately succeeds the currency_symbol. */
196 char p_sign_posn;
197 char n_sign_posn;
198 };
199 POSIX.1-2008 extensions to the locale API
201 POSIX.1-2008 standardized a number of extensions to the locale API,
202 based on implementations that first appeared in version 2.3 of the GNU
203 C library. These extensions are designed to address the problem that
204 the traditional locale APIs do not mix well with multithreaded applica‐
205 tions and with applications that must deal with multiple locales.
206 The extensions take the form of new functions for creating and manipu‐
208 lating locale objects (newlocale(3), freelocale(3), duplocale(3), and
209 uselocale(3)) and various new library functions with the suffix "_l"
210 (e.g., toupper_l(3)) that extend the traditional locale-dependent APIs
211 (e.g., toupper(3)) to allow the specification of a locale object that
212 should apply when executing the function.
213
215 The following environment variable is used by newlocale(3) and setlo‐
216 cale(3), and thus affects all unprivileged localized programs:
217 LOCPATH
219 A list of pathnames, separated by colons (':'), that should be
220 used to find locale data. If this variable is set, only the
221 individual compiled locale data files from LOCPATH and the sys‐
222 tem default locale data path are used; any available locale ar‐
223 chives are not used (see localedef(1)). The individual compiled
224 locale data files are searched for under subdirectories which
225 depend on the currently used locale. For example, when
226 en_GB.UTF-8 is used for a category, the following subdirectories
227 are searched for, in this order: en_GB.UTF-8, en_GB.utf8, en_GB,
228 en.UTF-8, en.utf8, and en.
229
231 /usr/lib/locale/locale-archive
232 Usual default locale archive location.
233 /usr/lib/locale
235 Usual default path for compiled individual locale files.
236
238 POSIX.1-2001.
239
241 iconv(1), locale(1), localedef(1), catopen(3), gettext(3), iconv(3),
242 localeconv(3), mbstowcs(3), newlocale(3), ngettext(3), nl_langinfo(3),
243 rpmatch(3), setlocale(3), strcoll(3), strfmon(3), strftime(3),
244 strxfrm(3), uselocale(3), wcstombs(3), locale(5), charsets(7), uni‐
245 code(7), utf-8(7)
246
248 This page is part of release 5.02 of the Linux man-pages project. A
249 description of the project, information about reporting bugs, and the
250 latest version of this page, can be found at
251 https://www.kernel.org/doc/man-pages/.
252Linux 2019-03-06 LOCALE(7)