VS2012 MFC CStdioFile ReadString 处理UTF8文档乱码的方法

CStdioFile 的ReadString读写UTF8会出现乱码现象。需要转换。

//转换函数

void CharToUTF8(CString &str)
{
    char *szBuf = new char[str.GetLength() + 1];//注意“+1”，char字符要求结束符，而CString没有
memset(szBuf, '\0',str.GetLength());


int i;
    for ( i = 0 ; i < str.GetLength(); i++)
    {
        szBuf[i] = (char)str.GetAt(i);
    }
szBuf[i] = '\0';//结束符。否则会在末尾产生乱码。
    
int nLen;
WCHAR *ptch;
CString strOut;
if(szBuf == NULL)
{
return ;
}
nLen = MultiByteToWideChar(CP_UTF8, 0, szBuf, -1, NULL, 0);//获得需要的宽字符字节数
ptch = new WCHAR[nLen];
memset(ptch, '\0', nLen);
MultiByteToWideChar(CP_UTF8, 0, szBuf, -1, ptch, nLen);
//str.Format(_T("%s"), ptch);
str = ptch;
if(NULL != ptch)
delete [] ptch;
ptch = NULL;


if(NULL != szBuf)
delete []szBuf;
szBuf = NULL;
return ;
}

void FileOP(LPCTSTR LRFileName)
{

CStdioFile mFileIn;
CString strTempLine;

if(!mFileIn.Open(_T(LRFileName), CFile::modeRead )) 
{
AfxMessageBox("找不到文件");
return ;
} 


while(mFileIn.ReadString(strTempLine)!=NULL)
{
CharToUTF8(strTempLine);

AfxMessageBox(strTempLine);

}
mFileIn.Close();
}