头文件<locale.h>定义了特定地域的设置，如日期格式和货币符号。
<locale.h>中声明了两个函数和一个类型，并且定义了一些宏。
Linux version 2.6.32-573.el6.x86_64中的<locale.h>源码：
/* Copyright (C) 1991,1992,1995-2002,2007,2009 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, write to the Free
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA. */
/*
* ISO C99 Standard: 7.11 Localization <locale.h>
*/
#ifndef _LOCALE_H
#define _LOCALE_H 1
#include <features.h>
#define __need_NULL
#include <stddef.h>
#include <bits/locale.h>
__BEGIN_DECLS
/* These are the possibilities for the first argument to setlocale.
The code assumes that the lowest LC_* symbol has the value zero. */
#define LC_CTYPE __LC_CTYPE
#define LC_NUMERIC __LC_NUMERIC
#define LC_TIME __LC_TIME
#define LC_COLLATE __LC_COLLATE
#define LC_MONETARY __LC_MONETARY
#define LC_MESSAGES __LC_MESSAGES
#define LC_ALL __LC_ALL
#define LC_PAPER __LC_PAPER
#define LC_NAME __LC_NAME
#define LC_ADDRESS __LC_ADDRESS
#define LC_TELEPHONE __LC_TELEPHONE
#define LC_MEASUREMENT __LC_MEASUREMENT
#define LC_IDENTIFICATION __LC_IDENTIFICATION
__BEGIN_NAMESPACE_STD
/* Structure giving information about numeric and monetary notation. */
struct lconv
{
/* Numeric (non-monetary) information. */
char *decimal_point; /* Decimal point character. */
char *thousands_sep; /* Thousands separator. */
/* Each element is the number of digits in each group;
elements with higher indices are farther left.
An element with value CHAR_MAX means that no further grouping is done.
An element with value 0 means that the previous element is used
for all groups farther left. */
char *grouping;
/* Monetary information. */
/* First three chars are a currency symbol from ISO 4217.
Fourth char is the separator. Fifth char is ‘\0‘. */
char *int_curr_symbol;
char *currency_symbol; /* Local currency symbol. */
char *mon_decimal_point; /* Decimal point character. */
char *mon_thousands_sep; /* Thousands separator. */
char *mon_grouping; /* Like `grouping‘ element (above). */
char *positive_sign; /* Sign for positive values. */
char *negative_sign; /* Sign for negative values. */
char int_frac_digits; /* Int‘l fractional digits. */
char frac_digits; /* Local fractional digits. */
/* 1 if currency_symbol precedes a positive value, 0 if succeeds. */
char p_cs_precedes;
/* 1 iff a space separates currency_symbol from a positive value. */
char p_sep_by_space;
/* 1 if currency_symbol precedes a negative value, 0 if succeeds. */
char n_cs_precedes;
/* 1 iff a space separates currency_symbol from a negative value. */
char n_sep_by_space;
/* Positive and negative sign positions:
0 Parentheses surround the quantity and currency_symbol.
1 The sign string precedes the quantity and currency_symbol.
2 The sign string follows the quantity and currency_symbol.
3 The sign string immediately precedes the currency_symbol.
4 The sign string immediately follows the currency_symbol. */
char p_sign_posn;
char n_sign_posn;
#ifdef __USE_ISOC99
/* 1 if int_curr_symbol precedes a positive value, 0 if succeeds. */
char int_p_cs_precedes;
/* 1 iff a space separates int_curr_symbol from a positive value. */
char int_p_sep_by_space;
/* 1 if int_curr_symbol precedes a negative value, 0 if succeeds. */
char int_n_cs_precedes;
/* 1 iff a space separates int_curr_symbol from a negative value. */
char int_n_sep_by_space;
/* Positive and negative sign positions:
0 Parentheses surround the quantity and int_curr_symbol.
1 The sign string precedes the quantity and int_curr_symbol.
2 The sign string follows the quantity and int_curr_symbol.
3 The sign string immediately precedes the int_curr_symbol.
4 The sign string immediately follows the int_curr_symbol. */
char int_p_sign_posn;
char int_n_sign_posn;
#else
char __int_p_cs_precedes;
char __int_p_sep_by_space;
char __int_n_cs_precedes;
char __int_n_sep_by_space;
char __int_p_sign_posn;
char __int_n_sign_posn;
#endif
};
/* Set and/or return the current locale. */
extern char *setlocale (int __category, __const char *__locale) __THROW;
/* Return the numeric/monetary information for the current locale. */
extern struct lconv *localeconv (void) __THROW;
__END_NAMESPACE_STD
#ifdef __USE_XOPEN2K8
/* The concept of one static locale per category is not very well
thought out. Many applications will need to process its data using
information from several different locales. Another application is
the implementation of the internationalization handling in the
upcoming ISO C++ standard library. To support this another set of
the functions using locale data exist which have an additional
argument.
Attention: all these functions are *not* standardized in any form.
This is a proof-of-concept implementation. */
/* Get locale datatype definition. */
# include <xlocale.h>
/* Return a reference to a data structure representing a set of locale
datasets. Unlike for the CATEGORY parameter for `setlocale‘ the
CATEGORY_MASK parameter here uses a single bit for each category,
made by OR‘ing together LC_*_MASK bits above. */
extern __locale_t newlocale (int __category_mask, __const char *__locale,
__locale_t __base) __THROW;
/* These are the bits that can be set in the CATEGORY_MASK argument to
`newlocale‘. In the GNU implementation, LC_FOO_MASK has the value
of (1 << LC_FOO), but this is not a part of the interface that
callers can assume will be true. */
# define LC_CTYPE_MASK (1 << __LC_CTYPE)
# define LC_NUMERIC_MASK (1 << __LC_NUMERIC)
# define LC_TIME_MASK (1 << __LC_TIME)
# define LC_COLLATE_MASK (1 << __LC_COLLATE)
# define LC_MONETARY_MASK (1 << __LC_MONETARY)
# define LC_MESSAGES_MASK (1 << __LC_MESSAGES)
# define LC_PAPER_MASK (1 << __LC_PAPER)
# define LC_NAME_MASK (1 << __LC_NAME)
# define LC_ADDRESS_MASK (1 << __LC_ADDRESS)
# define LC_TELEPHONE_MASK (1 << __LC_TELEPHONE)
# define LC_MEASUREMENT_MASK (1 << __LC_MEASUREMENT)
# define LC_IDENTIFICATION_MASK (1 << __LC_IDENTIFICATION)
# define LC_ALL_MASK (LC_CTYPE_MASK \
| LC_NUMERIC_MASK \
| LC_TIME_MASK \
| LC_COLLATE_MASK \
| LC_MONETARY_MASK \
| LC_MESSAGES_MASK \
| LC_PAPER_MASK \
| LC_NAME_MASK \
| LC_ADDRESS_MASK \
| LC_TELEPHONE_MASK \
| LC_MEASUREMENT_MASK \
| LC_IDENTIFICATION_MASK \
)
/* Return a duplicate of the set of locale in DATASET. All usage
counters are increased if necessary. */
extern __locale_t duplocale (__locale_t __dataset) __THROW;
/* Free the data associated with a locale dataset previously returned
by a call to `setlocale_r‘. */
extern void freelocale (__locale_t __dataset) __THROW;
/* Switch the current thread‘s locale to DATASET.
If DATASET is null, instead just return the current setting.
The special value LC_GLOBAL_LOCALE is the initial setting
for all threads and can also be installed any time, meaning
the thread uses the global settings controlled by `setlocale‘. */
extern __locale_t uselocale (__locale_t __dataset) __THROW;
/* This value can be passed to `uselocale‘ and may be returned by it.
Passing this value to any other function has undefined behavior. */
# define LC_GLOBAL_LOCALE ((__locale_t) -1L)
#endif
__END_DECLS
#endif /* locale.h */
1、宏：
LC_ALL 设置下面的所有选项。
LC_COLLATE 影响 strcoll 和 strxfrm 函数。
LC_CTYPE 影响所有字符函数
LC_MONETARY 影响 localeconv 函数提供的货币信息。
LC_NUMERIC 影响 localeconv 函数提供的小数点格式化和信息。
LC_TIME 影响 strftime 函数。
2、结构：
struct lconv {
char *decimal_point; //用于非货币值的小数点字符。
char *thousands_sep; //用于非货币值的千位分隔符。
char *grouping; //表示非货币量中每组数字大小的字符串。值为 0 意味着前一个值将应用于剩余的分组。
char *int_curr_symbol; //国际货币符号使用的字符串。
char *currency_symbol; //用于货币的本地符号。
char *mon_decimal_point; //用于货币值的小数点字符。
char *mon_thousands_sep; //用于货币值的千位分隔符。
char *mon_grouping; //表示货币值中每组数字大小的字符串。
char *positive_sign; //用于正货币值的字符。
char *negative_sign; //用于负货币值的字符。
char int_frac_digits; //国际货币值中小数点后要显示的位数。
char frac_digits; //货币值中小数点后要显示的位数。
char p_cs_precedes; //如果等于 1，则 currency_symbol 出现在正货币值之前。如果等于 0，则 currency_symbol 出现在正货币值之后。
char p_sep_by_space; //如果等于 1，则 currency_symbol 和正货币值之间使用空格分隔。如果等于 0，则 currency_symbol 和正货币值之间不使用空格分隔。
char n_cs_precedes; //如果等于 1，则 currency_symbol 出现在负货币值之前。如果等于 0，则 currency_symbol 出现在负货币值之后。
char n_sep_by_space; //如果等于 1，则 currency_symbol 和负货币值之间使用空格分隔。如果等于 0，则 currency_symbol 和负货币值之间不使用空格分隔。
char p_sign_posn; //表示正货币值中正号的位置。
char n_sign_posn; //表示负货币值中负号的位置。
} ;
3、函数：
3.1函数setlocale被用来修改或查询程序当前的整个区域设置或者其中的一部分
char * setlocale(int category,const char *locale);
参数：category为LC_ALL，LC_COLLATE等。locale若是空字符串 ""，则会使用系统环境变量的 locale 。若 locale 为零(NULL)，则不会改变地域化配置，返回当前的地域值，若系统尚未实作则返回 false。
返回值：成功，返回相应设置的地域化信息。字符串可能分配在静态存储区。失败，返回NULL
3.2函数localeconv获得包含本地数字及货币信息格式的数组
struct lconv *localeconv(void);
功能：返回当前地域设置的信息
返回值：返回一个指向struct lconv 类型结构体的指针。
例：
#include <assert.h>
#include <limits.h>
#include <locale.h>
#include <stdio.h>
#include <string.h>
static void testclocale(struct lconv *p)
{
assert(strcmp(p->currency_symbol,"")==0);
assert(strcmp(p->decimal_point,".")==0);
assert(strcmp(p->grouping,"")==0);
assert(strcmp(p->int_curr_symbol,"")==0);
assert(strcmp(p->mon_decimal_point,"")==0);
assert(strcmp(p->mon_grouping,"")==0);
assert(strcmp(p->mon_thousands_sep,"")==0);
assert(strcmp(p->negative_sign,"")==0);
assert(strcmp(p->positive_sign,"")==0);
assert(strcmp(p->thousands_sep,"")==0);
assert(p->frac_digits==CHAR_MAX);
assert(p->int_frac_digits==CHAR_MAX);
assert(p->n_cs_precedes==CHAR_MAX);
assert(p->n_sep_by_space==CHAR_MAX);
assert(p->n_sign_posn==CHAR_MAX);
assert(p->p_cs_precedes==CHAR_MAX);
assert(p->p_sep_by_space==CHAR_MAX);
assert(p->p_sign_posn==CHAR_MAX);
}
int main()
{
static int cats[]={LC_ALL,LC_COLLATE,LC_CTYPE,LC_MONETARY,LC_NUMERIC,LC_TIME};
struct lconv *p=NULL;
char buf[32],*s;
assert((p=localeconv())!=NULL);
testclocale(p);
assert((s=setlocale(LC_ALL,NULL))!=NULL);
assert(localeconv()!=NULL);
assert((s=setlocale(LC_MONETARY,"C"))!=NULL);
puts(strcmp(s,"C")?"Native local differs from \"C\"":"Native locale same as \"C\"");
assert(setlocale(LC_NUMERIC,"C")!=NULL);
assert((p=localeconv())!=NULL);
testclocale(p);
assert(setlocale(LC_ALL,buf)!=NULL);
assert((p=localeconv())!=NULL);
testclocale(p);
puts("sucess testing <locale.h>");
return (0);
}