Boost.Locale 之字符转换 gbk utf8 big5 string wstring等

Boost.Locale是一个库，它提供高质量的本地化的设施在C + +的方式。它最初是设计的一部分CppCMS - C + +的Web框架的项目，然后促成了提升。

Boost.Locale提供强大的工具，跨平台的本地化软件开发 - 这会谈到用户在其语言的软件。

提供的功能：

• 正确的大小写转换，大小写和规范化。
• 整理（排序），其中包括4 Unicode排序规则层面的支持。
• 日期，时间，时区和日历操作，格式化和分析，包括对日历比公历其他透明的支持。
• 边界分析字，词，句和换行符。
• 数字格式，拼写和语法分析。
• 货币格式和解析。
• 强大的邮件格式（字符串翻译），包括多种格式，使用GNU目录的支持。
• 字符集转换。
• 8位字符透明支持集，如拉丁文
• 支持的char和wchar_t的
• 对C + +0 x的实验性支持char16_t和char32_t字符串和数据流。

Boost.Locale提高和统一了标准库的API，它变得非常有用和方便开发跨平台的和“跨文化”软件的方式。

相关字符集转换函数功能摘要：

std::string boost::locale::conv::between	(	char const *	begin,
		char const *	end,
		std::string const &	to_encoding,
		std::string const &	from_encoding,
		method_type	how = default_method
	)

Convert a text in range [begin,end) to to_encoding from from_encoding

std::string boost::locale::conv::between	(	char const *	text,
		std::string const &	to_encoding,
		std::string const &	from_encoding,
		method_type	how = default_method
	)		[inline]

Convert a text to to_encoding from from_encoding

std::string boost::locale::conv::between	(	std::string const &	text,
		std::string const &	to_encoding,
		std::string const &	from_encoding,
		method_type	how = default_method
	)		[inline]

Convert a text to to_encoding from from_encoding

template<typename CharType >

std::string boost::locale::conv::from_utf	(	CharType const *	begin,
		CharType const *	end,
		std::string const &	charset,
		method_type	how = default_method
	)

convert UTF text in range [begin,end) to a text encoded with charset according to policy how

template<typename CharType >

std::string boost::locale::conv::from_utf	(	CharType const *	begin,
		CharType const *	end,
		std::locale const &	loc,
		method_type	how = default_method
	)

convert UTF text in range [begin,end) to a text encoded according to locale loc according to policy how

Note:

throws std::bad_cast if the loc does not have  info facet installed

template<typename CharType >

std::string boost::locale::conv::from_utf	(	std::basic_string< CharType > const &	text,
		std::string const &	charset,
		method_type	how = default_method
	)

Convert a text from charset to UTF string

template<typename CharType >

std::string boost::locale::conv::from_utf	(	CharType const *	text,
		std::string const &	charset,
		method_type	how = default_method
	)

Convert a text from UTF to charset

template<typename CharType >

std::string boost::locale::conv::from_utf	(	std::basic_string< CharType > const &	text,
		std::locale const &	loc,
		method_type	how = default_method
	)

Convert a text in UTF to locale encoding given by loc

Note:

throws std::bad_cast if the loc does not have  info facet installed

template<typename CharType >

std::string boost::locale::conv::from_utf	(	CharType const *	text,
		std::locale const &	loc,
		method_type	how = default_method
	)

Convert a text in UTF to locale encoding given by loc

Note:

throws std::bad_cast if the loc does not have  info facet installed

template<typename CharType >

std::basic_string<CharType> boost::locale::conv::to_utf	(	char const *	begin,
		char const *	end,
		std::string const &	charset,
		method_type	how = default_method
	)

convert string to UTF string from text in range [begin,end) encoded with charset according to policy how

template<typename CharType >

std::basic_string<CharType> boost::locale::conv::to_utf	(	char const *	begin,
		char const *	end,
		std::locale const &	loc,
		method_type	how = default_method
	)

convert string to UTF string from text in range [begin,end) encoded according to locale loc according to policy how

Note:

throws std::bad_cast if the loc does not have  info facet installed

template<typename CharType >

std::basic_string<CharType> boost::locale::conv::to_utf	(	std::string const &	text,
		std::string const &	charset,
		method_type	how = default_method
	)

convert a string text encoded with charset to UTF string

template<typename CharType >

std::basic_string<CharType> boost::locale::conv::to_utf	(	char const *	text,
		std::string const &	charset,
		method_type	how = default_method
	)

Convert a text from charset to UTF string

template<typename CharType >

std::basic_string<CharType> boost::locale::conv::to_utf	(	std::string const &	text,
		std::locale const &	loc,
		method_type	how = default_method
	)

Convert a text in locale encoding given by loc to UTF

Note:

throws std::bad_cast if the loc does not have  info facet installed

template<typename CharType >

std::basic_string<CharType> boost::locale::conv::to_utf	(	char const *	text,
		std::locale const &	loc,
		method_type	how = default_method
	)

Convert a text in locale encoding given by loc to UTF

Note:

throws std::bad_cast if the loc does not have  info facet installed

template<typename CharOut , typename CharIn >

std::basic_string<CharOut> boost::locale::conv::utf_to_utf	(	CharIn const *	begin,
		CharIn const *	end,
		method_type	how = default_method
	)

Convert a Unicode text in range [begin,end) to other Unicode encoding

template<typename CharOut , typename CharIn >

std::basic_string<CharOut> boost::locale::conv::utf_to_utf	(	CharIn const *	str,
		method_type	how = default_method
	)

Convert a Unicode NUL terminated string str other Unicode encoding

template<typename CharOut , typename CharIn >

std::basic_string<CharOut> boost::locale::conv::utf_to_utf	(	std::basic_string< CharIn > const &	str,
		method_type	how = default_method
	)

Convert a Unicode string str other Unicode encoding

简单示例：

1、between把 source 这个字串从BIG5 转换到 UTF-8：

 string source = "BIG5字符串";
 string s = boost::locale::conv::between( source, "UTF-8", "BIG5" );

2、to_utf可以输出 string ，也可以输出成 wstring。像下面的例子，就是把 sSource 这个 BIG-5 编码的字串，依序转换成 wstring 和 string 的字串。

 string sSource = "BIG-5字符串";
 wstring ws = boost::locale::conv::to_utf<wchar_t>( sSource, "BIG5" );
 string  ss = boost::locale::conv::to_utf<char>( sSource, "BIG5" );

3、from_utf 是把 UTF 字串（string 或wstring）、转换为特定编码的字串用的，他可以转换string或wstring 的字串，但是输出一定是string。

下面的例子，就是把 sSource 和 wSource 这两个 UTF 字串，都转换成 BIG-5 的 string 字串。

 string  sSource =  "字符串";
 wstring wSource = L"...";
 string  ss1 = boost::locale::conv::from_utf( wSource, "BIG5" );
 string  ss2 = boost::locale::conv::from_utf( sSource, "BIG5" );

4、utf_to_utf的目的，是在 UTF 的 string 字串和 wstring 字串之间做转换，下面的例子，就是把类型是string 的 sSource 转换成 wstring、并把类型是 wstring 的 wSource 转换成 string

 string  sSource =  "...";
 wstring wSource = L"...";
 wstring wStr = boost::locale::conv::utf_to_utf<wchar_t>( sSource );
 string  sStr = boost::locale::conv::utf_to_utf<char>( wSource );