C++ virtual function

没有使用virtual的情况：

#include <iostream>

using namespace std;
class Parent {

public:
    void show() {

        cout << "I'm parent" << endl;
    }
};

class child :public Parent {
public:
    void show() {
        cout << "I'm child" << endl;
    }
};

int main() {
    Parent *ptr = new child();
    ptr->show();
    system("pause");
    return 0;
}

OutputParent

think different，change world

当在base类中使用了virtual function时，我们就能访问用base类对象的指针，访问派生类的方法了。看下面：

#include <iostream>

using namespace std;
class Parent {

public:
    virtual void show() {

        cout << "I'm parent" << endl;
    }
};

class child :public Parent {
public:
    void show() {
        cout << "I'm child" << endl;
    }
};

int main() {
    Parent *parent_object_ptr = new child();
    parent_object_ptr->show();
    system("pause");
    return 0;
}

virtual function