c++ - C++ 中的值访问

Question

你好，

我有两个类 A 和 B， 这里 A 继承 B，现在我想从 A 访问 B 中的变量，我在 B 中包含 A header 并尝试访问但在 QObject 中显示一些错误。

是否可以这样访问..请帮忙

Answer 1

不确定我是否正确理解了您的问题....

class A {
public:
  int nValueA;
protected:
  int nValueB;
private:
  int nValueC;
};

class B : public A {
public:
    B();
    int x, y, z;
}; 
B::B(): 
x(nValueA), //-->OK
y(nValueB), //-->OK
z(nValueC)  //-->error due to child can't inherit parent's private member
{}

void main(){
  B object;
  object.nValueA = 888; //--> valid
  object.nValueB = 888; //--> error since protected member is not accessible
  object.nValueC = 888; //--> error since private member is not accessible
}

可能的解决方案:

class A {
public:
  int nValueA;
  int nValueB;
  int nValueC;
};