CString转换成char*的最佳方案

char * cs2ca(CString str){    char *ptr;    #ifdef _UNICODE    LONG len;    len = WideCharToMultiByte(CP_ACP, 0, str, -1, NULL, 0, NULL, NULL);    ptr = new char [len+1];    memset(ptr,0,len + 1);    WideCharToMultiByte(CP_ACP, 0, str, -1, ptr, len + 1, NULL, NULL);    #else    ptr = new char [str.GetAllocLength()+1];    sprintf(ptr,_T("%s"),str);    #endif    return ptr;}