LPSTR Convert(LPCSTR str, int sourceCodepage, int targetCodepage)
{
 int len=_tcslen(str);
 int unicodeLen=MultiByteToWideChar(sourceCodepage,0,str,-1,NULL,0);
 wchar_t* pUnicode;
 pUnicode=new wchar_t[unicodeLen+1];
 memset(pUnicode,0,(unicodeLen+1)*sizeof(wchar_t));
  
 MultiByteToWideChar(sourceCodepage,0,str,-1,(LPWSTR)pUnicode,unicodeLen);
 
 BYTE * pTargetData;
 int targetLen=WideCharToMultiByte(targetCodepage,0,(LPWSTR)pUnicode,-1,(char *)pTargetData,0,NULL,NULL);
 
 pTargetData=new BYTE[targetLen+1];
 memset(pTargetData,0,targetLen+1);
 
 WideCharToMultiByte(targetCodepage,0,(LPWSTR)pUnicode,-1,(char *)pTargetData,targetLen,NULL,NULL);
 
 LPSTR szResult=new TCHAR[targetLen+1];
 wsprintf(szResult,"%s",pTargetData);
 
 delete[] pUnicode;
 delete[] pTargetData;
 return szResult;
}

用法
編碼
Convert(str,936,CP_UTF8);
解碼
Convert(str,CP_UTF8,936);