使用c++11标准库转换字符编码

#include <stdio.h>
#include <locale>
#include <codecvt>

const std::string ws2s( const std::wstring& src )
{
std::locale sys_locale("");

const wchar_t* data_from = src.c_str();
const wchar_t* data_from_end = src.c_str() + src.size();
const wchar_t* data_from_next = 0;

int wchar_size = 4;
char* data_to = new char[(src.size() + 1) * wchar_size];
char* data_to_end = data_to + (src.size() + 1) * wchar_size;
char* data_to_next = 0;

memset( data_to, 0, (src.size() + 1) * wchar_size );

typedef std::codecvt<wchar_t, char, mbstate_t> convert_facet;
mbstate_t out_state = 0;
auto result = std::use_facet<convert_facet>(sys_locale).out(
out_state, data_from, data_from_end, data_from_next,
data_to, data_to_end, data_to_next );
if( result == convert_facet::ok )
{
std::string dst = data_to;
delete[] data_to;
return dst;
}
else
{
printf( "convert error!\n" );
delete[] data_to;
return std::string("");
}
}

const std::wstring s2ws( const std::string& src )
{
std::locale sys_locale("");

const char* data_from = src.c_str();
const char* data_from_end = src.c_str() + src.size();
const char* data_from_next = 0;

wchar_t* data_to = new wchar_t[src.size() + 1];
wchar_t* data_to_end = data_to + src.size() + 1;
wchar_t* data_to_next = 0;

wmemset( data_to, 0, src.size() + 1 );

typedef std::codecvt<wchar_t, char, mbstate_t> convert_facet;
mbstate_t in_state = 0;
auto result = std::use_facet<convert_facet>(sys_locale).in(
in_state, data_from, data_from_end, data_from_next,
data_to, data_to_end, data_to_next );
if( result == convert_facet::ok )
{
std::wstring dst = data_to;
delete[] data_to;
return dst;
}
else
{
printf( "convert error!\n" );
delete[] data_to;
return std::wstring(L"");
}
}

const std::string ws2utf8( const std::wstring& src )
{
std::wstring_convert<std::codecvt_utf8<wchar_t>> conv;
return conv.to_bytes( src );
}

const std::wstring utf8_2_ws( const std::string& src )
{
std::wstring_convert<std::codecvt_utf8<wchar_t> > conv;
return conv.from_bytes( src );
}

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