std：映射继承与MFC问题

I have a base class which has a protected member:map<mstring,mstring>mstring is a derived class from std::string, which includes somefunctionality to cope with MFC. It works fine in the base class, but when I try to use it in a derivedclass, it gives me an error message. C:\Program Files\Microsoft Visual Studio .NET2003\Vc7\include\functional(139): error C2678: binary ''<'' : no operatorfound which takes a left-hand operand of type ''const mstring'' (or thereis no acceptable conversion) In my class there is an operator < overload. I took that out to see itthat could be the problem, but I get the same message. I then tried atest map<string,string> and I get the same message. I tried messingwith map < mstring, mstring > (adding the spaces, because sometimeswith a template of containers VC++ needs certain spaces). Nothing. The funny thing is that if I use the mfc CString class instead, itworks, but I don''t want to redo the extra functionality deriving fromCString. Any help? Thanks,Jay 推荐答案 Donkeylung写道：Donkeylung wrote: C：\Program Files \ Microsoft Visual Studio .NET 2003 \Vc7 \include \ functional（139）：错误C2678：二进制''<''：找不到运算符，它采用类型''const mstring'的左手操作数'（或者是不可接受的转换） 在我班上有一个操作员<超载。 C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\include\functional(139): error C2678: binary ''<'' : no operator found which takes a left-hand operand of type ''const mstring'' (or there is no acceptable conversion) In my class there is an operator < overload. 你能否展示两件事： 1）你如何从std :: string派生出来？ 2）你如何实现运营商<在mstring？ 3）如果std :: string占有，你如何使用map？ Can you please show two things:1) How you derive from std::string?2) How do you implement operator < in mstring?3) How do you use map in case of std::string possession? 1） typedef class mfc_string： public string { ..... } mstring; 2） 这是2运营商<重载（他们最初没有采取 const参数的方式，我仍然得到错误） mfc_string mfc_string :: operator<（const mfc_string& p） { double left = atof（this-> c_str（））; double right = atof（p.c_str（））; char enter_string [50]; sprintf（enter_string，"％f"，left-right）; return mstring（enter_string）; } mfc_string mfc_string :: operator<（const double& right） { double left = atof（this-> c_str（））; char enter_string [50]; sprintf（enter_string，"％f"，left-right）; 返回mstring（enter_string）; } 3）当我使用map< string，string>时，它仅用于测试。 另外请注意，只有当我使用[]表示法时才会出现错误。如果它是访问先前定义的密钥（在基础 类中，它没关系）或者是否正在创建新密钥，那么无关紧要派生 等级。 谢谢， jay 1)typedef class mfc_string :public string{.....}mstring;2)Here are the 2 operator < overloads (they originally did not takeconst arguments either way, I still get the error)mfc_string mfc_string::operator<(const mfc_string& p){double left = atof(this->c_str());double right = atof(p.c_str());char enter_string[50];sprintf(enter_string, "%f", left-right);return mstring(enter_string);} mfc_string mfc_string::operator<(const double& right){double left = atof(this->c_str());char enter_string[50];sprintf(enter_string, "%f", left-right);return mstring(enter_string);} 3) When I used map<string, string>, it was only for a test. Another note, the error only occurs when I use the [] notation. Itdoesn''t matter if it is accessing a previously defined key(in the baseclass, where it is fine) or if is creating a new key in the derivedclass. thanks,jay Donkeylungéérit：Donkeylung a écrit : mstring是来自std :: string的派生类 mstring is a derived class from std::string std :: string并不意味着要派生，它没有任何虚拟功能。 因此，如果你尝试这样做，你可能会遇到问题。 std::string isn''t meant to be derived, it doesn''t have any virtual function.Thus you will probably have issues if you try doing that. 这篇关于std：映射继承与MFC问题的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！