C++类继承中的虚方法

#include <bits/stdc++.h>
using namespace std;

class A {
    public:
        void Show() {
            cout << "A" << endl;
        }
} ;

class B : public A {
    public:
        virtual void Show() {
            cout << "B" << endl;
        }
} ;

class C : public B {
    public:
        void Show() {
            cout << "C" << endl;
        }
} ;

int main() {
    A a; B b; C c;
    A &s1 = b; A &s2 = c;
    B &t1 = b; B &t2 = c;
    s1.Show(); s2.Show();
    t1.Show(); t2.Show();
    return 0;
}

#include <bits/stdc++.h>
using namespace std;

class A {
    public:
        virtual void Show() { // 将virtual去掉运行做对比
            cout << "A" << endl;
        }
} ;

class B : public A {
    public:
        virtual void Show() {
            cout << "B" << endl;
        }
} ;

class C : public A {
    public:
        void Show() {
            cout << "C" << endl;
        }
} ;

class D : public A {
} ;

int main() {
    ios::sync_with_stdio(0);
    A a; B b; C c; D d;
    A &t1 = a; A &t2 = b; A &t3 = c; A &t4 = d;
    t1.Show(); t2.Show(); t3.Show(); t4.Show();
    a.Show(); b.Show(); c.Show(); d.Show();
    return 0;
}

——written by Lyon