當我將父方法作爲派生對象調用時出現C++錯誤

Question

#include <iostream> 
#include <string> 
using namespace std; 

class parent 
{ 
    int x=0; 
    public: 
    int getx() 
    { 
     return x; 
    } 
}; 

class child : public parent 
{ 
    int x=7; 
}; 
int main() 
{ 
    parent cat; 
    cout << cat.getx(); 
    child s; 
    cout << s.getx(); //stops working here 
    return 0; 
} 

這是我遇到的問題的示例。爲什麼不打印7當我調用cout < < getx（）作爲派生對象？

Answer 1

#include <iostream> 
#include <string> 

class parent 
{ 
protected: 
    int m_x; 
public: 
    parent(int x = 0) : m_x(x) {} 
    int getx(){return m_x;} 
}; 
class child : public parent 
{ 
public: 
    child():parent(7){} 
}; 
int main() 
{ 
    parent cat; 
    std::cout << cat.getx() << std::endl; 

    child s; 
    std::cout << s.getx() << std::endl; 

    return 0; 
} 

結果

dgs@dhome:~/Develop/Test2$ make getx 
g++  getx.cpp -o getx 
dgs@dhome:~/Develop/Test2$ ./getx 
0 
7