static void split(const string& src, const string& separator, vector<string>& dest)  
    {  
        string str = src;  
        string substring;  
        string::size_type start = 0, index;  
        do  
        {  
            index = str.find_first_of(separator,start);  
            if (index != string::npos)  
            {      
                substring = str.substr(start,index-start);  
                dest.push_back(substring);  
                start = str.find_first_not_of(separator,index);  
                if (start == string::npos) return;  
            }  
        }while(index != string::npos);  
        //the last token  
        substring = str.substr(start);  
        dest.push_back(substring);  
    }