父类指针访问子类成员变量

1、父类指针获取子类成员变量

#include <iostream>

using namespace std;

class Base {
public:
    virtual void get() {}
};

class Derive :public Base
{
public:
    Derive(){}
    void get() {
        printf("The third element is %d
", _x[2]);
    };
    int _x[6] = { 0,1,2,3,4,5 };
};

int main()
{
    Base *base = new Derive();
    base->get();

    return 0;
}

2、类型转换

#include <iostream>

using namespace std;

class Base
{
public:
    void virtual Func()
    {
        cout << "Base
";
    }
};

class Derived : public Base
{
public:
    void Func()
    {
        cout << "Derived
";
    }

    void NewFunc()
    {
        cout << "New func
";
    }
    int x[5] = { 0,1,2,3,4 };
};

int main()
{
    Base* b = new Derived();
    b->Func();
    
    Derived* d =dynamic_cast<Derived*>(b) ;
    // 不安全的转换
    //Derived* d = (Derived*)b;
    d->NewFunc();
    cout << d->x[2] << endl;

    return 0;
}