error: request for member is ambiguous c++;

Question

我已经在 Whosebug 上查看了几个类似的问题，但没有任何帮助。我不明白为什么我的 class NetflixCanada 中的关键字 using 不能解决歧义。

我想达到的目标：第二次访问来自 NetflixUkraine 的私有方法 class.

无论如何，这是代码：

#include <iostream>
using namespace std;

void greetings(){
    cout << "\e[1mHi! This is a Netflix country review:\e[0m\n";
}

class NetflixUkraine {
    private:
    string mostPplrBrowserFrNTflx;

    public:
    string countryName; 
    int amountMedia = 5000;
    void uniqueMedia(){
        cout << "We have john Wick II\n";
    }
    
        void setBrowser(string amostPplrBrowserFrNTflx){
        if (amostPplrBrowserFrNTflx == "Chrome" || amostPplrBrowserFrNTflx == "Firefox" || 
        amostPplrBrowserFrNTflx == "Safari" || amostPplrBrowserFrNTflx == "Opera"){

            mostPplrBrowserFrNTflx = amostPplrBrowserFrNTflx;
        }

        else {
            mostPplrBrowserFrNTflx = "\nCannot define a web browser!\n";
        }
        }


        string getBrowser(){
            return mostPplrBrowserFrNTflx;
        }
};

class NetflixPoland: public NetflixUkraine { 
   public:
    void uniqueMedia(){
        cout << "We have john Wick II and III\n"; //method overriding
    }
   

   string doPolesLoveNtflx(bool answer){ //extending inheritance    
       if (answer == 1){
            return "Poles love Netflix";
       }
       else{
            return "Poles don't love Netflix";
       }
   }
};

class NetflixCanada: public NetflixUkraine, public NetflixPoland{
    public:
    using NetflixUkraine::setBrowser;
};

int main()
{
    greetings();

    //printing output
    NetflixUkraine library1;
    library1.countryName = "Ukraine";
    cout<< library1.countryName<<endl << library1.amountMedia << endl;
    library1.uniqueMedia(); //printing out the unique media


    NetflixPoland library3;
    library3.countryName = "\nPoland";
    cout << library3.countryName<< endl;
    library3.uniqueMedia();
    cout << library3.doPolesLoveNtflx(true) << endl;
    
    //adding a fav browser for watching Netflix
    library3.setBrowser("Chrome");
    cout << "most popular browser for watching Netflix: " << library3.getBrowser() << endl;

    NetflixCanada library4;
    library4.NetflixUkraine::setBrowser ("Chrome");

    return 0;
}

输出：


[12inheritance.cpp 2020-10-10 11:41:07.556]
,,12inheritance.cpp:65:7: warning: direct base ‘NetflixUkraine’ inaccessible in ‘NetflixCanada’ due to ambiguity
   65 | class NetflixCanada: public NetflixUkraine, public NetflixPoland{
      |       ^~~~~~~~~~~~~
12inheritance.cpp: In function ‘int main()’:
12inheritance.cpp:96:30: error: ‘NetflixUkraine’ is an ambiguous base of ‘NetflixCanada’
   96 |     library4.NetflixUkraine::setBrowser ("Chrome");
      |                              ^~~~~~~~~~

Answer 1

你的编译器无法区分：

Netflix加拿大::Netflix乌克兰::setBrowser

和

Netflix加拿大::Netflix波兰::Netflix乌克兰::setBrowser

如评论中所述，请阅读 "The deadly diamond of death"

error: request for member is ambiguous c++;

error: request for member is ambiguous c++;

c++

class

methods

ambiguity