本地化库
本地环境设施包含字符分类和字符串校对、数值、货币及日期/时间格式化和分析，以及消息取得的国际化支持。本地环境设置控制流 I/O 、正则表达式库和 C++ 标准库的其他组件的行为。
平面类别
从输入字符序列中解析时间/日期值到 std::tm 中
std::time_get
|----------------------------------------------------------------------------------------------|---|---|
| template< class CharT, class InputIt = std::istreambuf_iterator<CharT> > class time_get; | | |
类模板 std::time_get 封装日期和时间分析规则。 I/O 操纵符 std::get_time 用 I/O 流的 locale 的 std::time_get 平面转换文本输入为 std::tm 对象。
继承图
类型要求
|---|---|---|
| - InputIt 必须满足遗留输入迭代器 (LegacyInputIterator) 的要求。 |||
特化
标准库提供二个孤立（独立于本地环境的）全特化和二个部分特化：
|-----------------------------------|------------------------|
| 定义于头文件 <locale> ||
| std::time_get<char> | 分析日期和时间的窄字符串表示 |
| std::time_get<wchar_t> | 分析日期和时间的宽字符串表示 |
| std::time_get<char, InputIt> | 用定制输入迭代器分析日期和时间的窄字符串表示 |
| std::time_get<wchar_t, InputIt> | 用定制输入迭代器分析日期和时间的宽字符串表示 |
另外， C++ 程序中构造的每个 locale 对象都实装这些特化的其自身（本地环境限定）版本。
成员类型
|-------------|-----------|
| 成员类型 | 定义 |
| char_type | CharT |
| iter_type | InputIt |
调用 do_get_weekday & 从输入流释出星期的日名
std::time_get<CharT,InputIt>::get_weekday,
std::time_get<CharT,InputIt>::do_get_weekday
|---------------------------------------------------------------------------------------------------------------------------------------------------|-----|---|
| public: iter_type get_weekday( iter_type beg, iter_type end, std::ios_base& str, std::ios_base::iostate& err, std::tm* t) const; | (1) | |
| protected: virtual iter_type do_get_weekday( iter_type beg, iter_type end, std::ios_base& str, std::ios_base::iostate& err, std::tm* t) const; | (2) | |
-
公开成员函数，调用最终导出类的受保护虚成员函数
do_get_weekday。 -
从字符序列
[beg, end)读取出相继字符，用此 locale 所期待的星期默认格式，同函数 std::get_time 、 time_get::get 和 POSIX 函数strptime()所用的 "%a" ，分析出星期名（可能为缩写）。
若它找到缩写名，则它持续读取，直至消耗尽完整名的字符，或找到不为期待的字符，后一情况下即使首段字符为合法缩写也分析失败。
存储分析得到的星期于 std::tm 域 t->tm_wday 。
若在读到合法星期名前抵达尾迭代器，则函数设置 err 中的 std::ios_base::eofbit 。若遇到分析错误，则函数设置 err 中的 std::ios_base::failbit 。
参数
|-----|---|---------------------------------------------------------------------|
| beg | - | 指代要分析的序列起始的迭代器 |
| end | - | 要分析的序列的尾后一位置迭代器 |
| str | - | 此函数在需要时用以获得 locale 平面的流对象，例如用 std::ctype 跳过空白符或用 std::collate 比较字符串 |
| err | - | 此函数所修改以指示错误的流错误标志对象 |
| t | - | 指向 std::tm 对象的指针，该对象将保有此函数调用结果 |
返回值
指向 [beg, end) 中辨识为合法星期名一部分的末字符后一位置的迭代器。
注意
此函数通常不区别大小写
若遇到分析错误，则此函数的大多数实现保留 *t 不修改。
调用示例 windows
#include <iostream>
#include <sstream>
#include <locale>
#include <iomanip>
#include <vector>
#include <algorithm>
#include <iterator>
#include <Windows.h>
std::vector<std::wstring> locals;
BOOL CALLBACK MyFuncLocaleEx(LPWSTR pStr, DWORD dwFlags, LPARAM lparam)
{
locals.push_back(pStr);
return TRUE;
}
std::string stows(const std::wstring& ws)
{
std::string curLocale = setlocale(LC_ALL, NULL); // curLocale = "C";
setlocale(LC_ALL, "chs");
const wchar_t* _Source = ws.c_str();
size_t _Dsize = 2 * ws.size() + 1;
char *_Dest = new char[_Dsize];
memset(_Dest, 0, _Dsize);
wcstombs(_Dest, _Source, _Dsize);
std::string result = _Dest;
delete[]_Dest;
setlocale(LC_ALL, curLocale.c_str());
return result;
}
void try_get_wday(const std::string& str)
{
std::cout << "Parsing the weekday out of '" << str <<
"' in the locale " << std::locale().name() << ' ';
std::istringstream istringstream(str);
std::ios_base::iostate err = std::ios_base::goodbit;
std::tm tm;
std::istreambuf_iterator<char> ret =
std::use_facet<std::time_get<char>>(istringstream.getloc()).get_weekday(
{istringstream}, {}, istringstream, err, &tm);
istringstream.setstate(err);
std::istreambuf_iterator<char> last{};
if (istringstream)
{
std::cout << "Successfully parsed, weekday number is " << tm.tm_wday;
if (ret != last)
{
std::cout << " Remaining content: ";
std::copy(ret, last, std::ostreambuf_iterator<char>(std::cout));
}
else
{
std::cout << " the input was fully consumed";
}
}
else
{
std::cout << "Parse failed. Unparsed string: ";
std::copy(ret, last, std::ostreambuf_iterator<char>(std::cout));
}
std::cout << std::endl;
}
int main()
{
EnumSystemLocalesEx(MyFuncLocaleEx, LOCALE_ALTERNATE_SORTS, NULL, NULL);
for (std::vector<std::wstring>::const_iterator str = locals.begin();
str != locals.end(); ++str)
{
std::locale::global(std::locale(stows(*str)));
try_get_wday("Sunday");
try_get_wday("星期五");
}
return 0;
}
输出
Parsing the weekday out of 'Sunday' in the locale de-DE_phoneb Parse failed. Unparsed string: unday
Parsing the weekday out of 'D??ú??' in the locale de-DE_phoneb Parse failed. Unparsed string: D??ú??
Parsing the weekday out of 'Sunday' in the locale es-ES_tradnl Parse failed. Unparsed string: Sunday
Parsing the weekday out of 'D??ú??' in the locale es-ES_tradnl Parse failed. Unparsed string: D??ú??
Parsing the weekday out of 'Sunday' in the locale hu-HU_technl Parse failed. Unparsed string: unday
Parsing the weekday out of '???ú??' in the locale hu-HU_technl Parse failed. Unparsed string: ???ú??
Parsing the weekday out of 'Sunday' in the locale ja-JP_radstr Parse failed. Unparsed string: Sunday
Parsing the weekday out of 'Sunday' in the locale ka-GE_modern Parse failed. Unparsed string: Sunday
Parsing the weekday out of '星期五' in the locale ka-GE_modern Parse failed. Unparsed string: 星期五
Parsing the weekday out of 'Sunday' in the locale x-IV_mathan Successfully parsed, weekday number is 0 the input was fully consumed
Parsing the weekday out of 'D??ú??' in the locale x-IV_mathan Parse failed. Unparsed string: D??ú??
Parsing the weekday out of 'Sunday' in the locale zh-CN_phoneb Parse failed. Unparsed string: Sunday
Parsing the weekday out of '星期五' in the locale zh-CN_phoneb Successfully parsed, weekday number is 5 the input was fully consumed
Parsing the weekday out of 'Sunday' in the locale zh-CN_stroke Parse failed. Unparsed string: Sunday
Parsing the weekday out of '星期五' in the locale zh-CN_stroke Successfully parsed, weekday number is 5 the input was fully consumed
Parsing the weekday out of 'Sunday' in the locale zh-HK_radstr Parse failed. Unparsed string: Sunday
Parsing the weekday out of '陎?拻' in the locale zh-HK_radstr Parse failed. Unparsed string: 陎?拻
Parsing the weekday out of 'Sunday' in the locale zh-MO_radstr Parse failed. Unparsed string: Sunday
Parsing the weekday out of '陎?拻' in the locale zh-MO_radstr Parse failed. Unparsed string: 陎?拻
Parsing the weekday out of 'Sunday' in the locale zh-MO_stroke Parse failed. Unparsed string: Sunday
Parsing the weekday out of '陎?拻' in the locale zh-MO_stroke Parse failed. Unparsed string: 陎?拻
Parsing the weekday out of 'Sunday' in the locale zh-SG_phoneb Parse failed. Unparsed string: Sunday
Parsing the weekday out of '星期五' in the locale zh-SG_phoneb Successfully parsed, weekday number is 5 the input was fully consumed
Parsing the weekday out of 'Sunday' in the locale zh-SG_stroke Parse failed. Unparsed string: Sunday
Parsing the weekday out of '星期五' in the locale zh-SG_stroke Successfully parsed, weekday number is 5 the input was fully consumed
Parsing the weekday out of 'Sunday' in the locale zh-TW_pronun Parse failed. Unparsed string: Sunday
Parsing the weekday out of '陎?拻' in the locale zh-TW_pronun Parse failed. Unparsed string: 陎?拻
Parsing the weekday out of 'Sunday' in the locale zh-TW_radstr Parse failed. Unparsed string: Sunday
Parsing the weekday out of '陎?拻' in the locale zh-TW_radstr Parse failed. Unparsed string: 陎?拻