man3/setlocale.3

   1 .\" (c) 1993 by Thomas Koenig (ig25@rz.uni-karlsruhe.de)
   2 .\" and 1999 by Bruno Haible (haible@clisp.cons.org)
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  24 .\" Modified Sat Jul 24 18:20:12 1993 by Rik Faith (faith@cs.unc.edu)
  25 .\" Modified Tue Jul 15 16:49:10 1997 by Andries Brouwer (aeb@cwi.nl)
  26 .\" Modified Sun Jul  4 14:52:16 1999 by Bruno Haible (haible@clisp.cons.org)
  27 .\" Modified Tue Aug 24 17:11:01 1999 by Andries Brouwer (aeb@cwi.nl)
  28 .\" Modified Tue Feb  6 03:31:55 2001 by Andries Brouwer (aeb@cwi.nl)
  29 .\"
  30 .TH SETLOCALE 3  1999-07-04 "GNU" "Linux Programmer's Manual"
  31 .SH NAME
  32 setlocale \- set the current locale
  33 .SH SYNOPSIS
  34 .nf
  35 .B #include <locale.h>
  36 .sp
  37 .BI "char *setlocale(int " category ", const char *" locale );
  38 .fi
  39 .SH DESCRIPTION
  40 The
  41 .BR setlocale ()
  42 function is used to set or query the program's current locale.
  43 .PP
  44 If
  45 .I locale
  46 is not NULL,
  47 the program's current locale is modified according to the arguments.
  48 The argument
  49 .I category
  50 determines which parts of the program's current locale should be modified.
  51 .TP
  52 .B LC_ALL
  53 for all of the locale.
  54 .TP
  55 .B LC_COLLATE
  56 for regular expression matching (it determines the meaning
  57 of range expressions and equivalence classes) and string collation.
  58 .TP
  59 .B LC_CTYPE
  60 for regular expression matching, character classification, conversion,
  61 case-sensitive comparison, and wide character functions.
  62 .TP
  63 .B LC_MESSAGES
  64 for localizable natural-language messages.
  65 .TP
  66 .B LC_MONETARY
  67 for monetary formatting.
  68 .TP
  69 .B LC_NUMERIC
  70 for number formatting (such as the decimal point and the thousands separator).
  71 .TP
  72 .B LC_TIME
  73 for time and date formatting.
  74 .PP
  75 The argument
  76 .I locale
  77 is a pointer to a character string containing the
  78 required setting of
  79 .IR category .
  80 Such a string is either a well-known constant like "C" or "da_DK"
  81 (see below), or an opaque string that was returned by another call of
  82 .BR setlocale ().
  83 .PP
  84 If
  85 .I locale
  86 is
  87 .BR """""" ,
  88 each part of the locale that should be modified is set according to the
  89 environment variables.
  90 The details are implementation dependent.
  91 For glibc, first
  92 .\" [This is false on my system - must check which library versions do this]
  93 .\" if
  94 .\" .I category
  95 .\" is LC_MESSAGES, the environment variable LANGUAGE is inspected,
  96 .\" then
  97 (regardless of
  98 .IR category ),
  99 the environment variable
 100 .B LC_ALL
 101 is inspected,
 102 next the environment variable with the same name as the category
 103 .RM ( LC_COLLATE ,
 104 .BR LC_CTYPE ,
 105 .BR LC_MESSAGES ,
 106 .BR LC_MONETARY ,
 107 .BR LC_NUMERIC ,
 108 .BR LC_TIME )
 109 and finally the environment variable
 110 .BR LANG .
 111 The first existing environment variable is used.
 112 If its value is not a valid locale specification, the locale
 113 is unchanged, and
 114 .BR setlocale ()
 115 returns NULL.
 116 .\" The environment variable LANGUAGE may contain several, colon-separated,
 117 .\" locale names.
 118 .PP
 119 The locale
 120 .B """C"""
 121 or
 122 .B """POSIX"""
 123 is a portable locale; its
 124 .BR LC_CTYPE
 125 part corresponds to the 7-bit ASCII
 126 character set.
 127 .PP
 128 A locale name is typically of the form
 129 .IR language "[_" territory "][." codeset "][@" modifier "],"
 130 where
 131 .I language
 132 is an ISO 639 language code,
 133 .I territory
 134 is an ISO 3166 country code, and
 135 .I codeset
 136 is a character set or encoding identifier like
 137 .B "ISO-8859-1"
 138 or
 139 .BR "UTF-8" .
 140 For a list of all supported locales, try "locale \-a", cf.\&
 141 .BR locale (1).
 142 .PP
 143 If
 144 .I locale
 145 is NULL, the current locale is only queried, not modified.
 146 .PP
 147 On startup of the main program, the portable
 148 .B """C"""
 149 locale is selected as default.
 150 A program may be made portable to all locales by calling
 151 .B setlocale(LC_ALL, """""")
 152 after program  initialization, by using the values returned
 153 from a
 154 .BR localeconv (3)
 155 call
 156 for locale-dependent information, by using the multi-byte and wide
 157 character functions for text processing if
 158 .BR "MB_CUR_MAX > 1" ,
 159 and by using
 160 .BR strcoll (3) ,
 161 .BR wcscoll (3)
 162 or
 163 .BR strxfrm (3),
 164 .BR wcsxfrm (3)
 165 to compare strings.
 166 .SH "RETURN VALUE"
 167 A successful call to
 168 .BR setlocale ()
 169 returns an opaque string that corresponds to the locale set.
 170 This string may be allocated in static storage.
 171 The string returned is such that a subsequent call with that string
 172 and its associated category will restore that part of the process's
 173 locale.
 174 The return value is NULL if the request cannot be honored.
 175 .SH "CONFORMING TO"
 176 C89, C99, POSIX.1-2001.
 177 .SH NOTES
 178 Linux (that is, GNU libc) supports the portable locales
 179 .BR """C""" " and " """POSIX""" .
 180 In the good old days there used to be support for
 181 the European Latin-1
 182 .B """ISO-8859-1"""
 183 locale (e.g., in libc-4.5.21 and libc-4.6.27), and the Russian
 184 .B """KOI-8"""
 185 (more precisely, "koi-8r") locale (e.g., in libc-4.6.27),
 186 so that having an environment variable \fILC_CTYPE=ISO-8859-1\fP
 187 sufficed to make
 188 .BR isprint (3)
 189 return the right answer.
 190 These days non-English speaking Europeans have to work a bit harder,
 191 and must install actual locale files.
 192 .SH "SEE ALSO"
 193 .BR locale (1),
 194 .BR localedef (1),
 195 .BR isalpha (3),
 196 .BR localeconv (3),
 197 .BR nl_langinfo (3),
 198 .BR rpmatch (3),
 199 .BR strcoll (3),
 200 .BR strftime (3),
 201 .BR charsets (7),
 202 .BR locale (7)