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;  
}