windows ASCII,UTF-8,Unicode字符串相互转换

#include<string>
#include<windows.h>
#include<vector>
using namespace std;

//utf8 转 Unicode

std::wstring Utf82Unicode(const std::string& utf8string)
{
int widesize = ::MultiByteToWideChar(CP_UTF8, 0, utf8string.c_str(), -1, NULL, 0);
if (widesize == ERROR_NO_UNICODE_TRANSLATION)
{
throw std::exception("Invalid UTF-8 sequence.");
}
if (widesize == 0)
{
throw std::exception("Error in conversion.");
}

std::vector<wchar_t> resultstring(widesize);

int convresult = ::MultiByteToWideChar(CP_UTF8, 0, utf8string.c_str(), -1, &resultstring[0], widesize);

if (convresult != widesize)
{
throw std::exception("La falla!");
}

return std::wstring(&resultstring[0]);
}

//unicode 转为 ascii

std::string WideByte2Acsi(std::wstring& wstrcode)
{
int asciisize = ::WideCharToMultiByte(CP_OEMCP, 0, wstrcode.c_str(), -1, NULL, 0, NULL, NULL);
if (asciisize == ERROR_NO_UNICODE_TRANSLATION)
{
throw std::exception("Invalid UTF-8 sequence.");
}
if (asciisize == 0)
{
throw std::exception("Error in conversion.");
}
std::vector<char> resultstring(asciisize);
int convresult =::WideCharToMultiByte(CP_OEMCP, 0, wstrcode.c_str(), -1, &resultstring[0], asciisize, NULL, NULL);

if (convresult != asciisize)
{
throw std::exception("La falla!");
}

return std::string(&resultstring[0]);
}

//utf-8 转 ascii

std::string UTF_82ASCII(std::string& strUtf8Code)
{
std::string strRet("");
//先把 utf8 转为 unicode
std::wstring wstr = Utf82Unicode(strUtf8Code);
//最后把 unicode 转为 ascii
strRet = WideByte2Acsi(wstr);
return strRet;
}

///////////////////////////////////////////////////////////////////////

//ascii 转 Unicode

std::wstring Acsi2WideByte(std::string& strascii)
{
int widesize = MultiByteToWideChar (CP_ACP, 0, (char*)strascii.c_str(), -1, NULL, 0);
if (widesize == ERROR_NO_UNICODE_TRANSLATION)
{
throw std::exception("Invalid UTF-8 sequence.");
}
if (widesize == 0)
{
throw std::exception("Error in conversion.");
}
std::vector<wchar_t> resultstring(widesize);
int convresult = MultiByteToWideChar (CP_ACP, 0, (char*)strascii.c_str(), -1, &resultstring[0], widesize);

if (convresult != widesize)
{
throw std::exception("La falla!");
}

return std::wstring(&resultstring[0]);
}

//Unicode 转 Utf8

std::string Unicode2Utf8(const std::wstring& widestring)
{
int utf8size = ::WideCharToMultiByte(CP_UTF8, 0, widestring.c_str(), -1, NULL, 0, NULL, NULL);
if (utf8size == 0)
{
throw std::exception("Error in conversion.");
}

std::vector<char> resultstring(utf8size);

int convresult = ::WideCharToMultiByte(CP_UTF8, 0, widestring.c_str(), -1, &resultstring[0], utf8size, NULL, NULL);

if (convresult != utf8size)
{
throw std::exception("La falla!");
}

return std::string(&resultstring[0]);
}

//ascii 转 Utf8

std::string ASCII2UTF_8(std::string& strAsciiCode)
{
std::string strRet("");
//先把 ascii 转为 unicode
std::wstring wstr = Acsi2WideByte(strAsciiCode);
//最后把 unicode 转为 utf8
strRet = Unicode2Utf8(wstr);
return strRet;
}