error: no match for 'operator<' (operand types are 'const Request_Info' and 'const Request_Info')xxxxxxx

代码：

　　 Request_Info requestInfo;
    requestInfo.askTYpe = askType;
    requestInfo.askName = _getAskName(askType, jsonStr);
    if(m_askIdMap.count(requestInfo) < 1){ //编译此代码报错
        std::cout << "no match request:" << askType << "," << jsonStr;
    }else {
    }

原因分析：

执行std::map.count()函数的时候会对key的大小做比较，作为自定义类型Request_Info，本身无法做大小比较。

解决方案：

1.换一个能够大小比较的类型做map的key值。

2.为自定义类型增加<操作符重载函数，如下所示：

    struct Request_Info{
    std::string     askTYpe;            //请求、成功、失败
    std::string     askName;            //SelectFilebyMultiKey、ShowRootDirectory等
    bool operator<(const struct Request_Info& requestInfo){
        bool ret = false;
        if(askName<requestInfo.askName){
            ret = true;
        }else if(askName == requestInfo.askName){
            if(askTYpe < requestInfo.askTYpe){
                ret = true;
            }
        }
        return ret;
    }
    friend bool operator<(const struct Request_Info& req1, const struct Request_Info& req2){
        bool ret = false;
        if(req1.askName<req2.askName){
            ret = true;
        }else if(req1.askName == req2.askName){
            if(req1.askTYpe < req2.askTYpe){
                ret = true;
            }
        }
        return ret;
    }
};