52virtualfnc_crrules.cpp

#include <iostream>
#include <cstring>

using namespace std;

class CWH
{
protected:
    string title;
    float rating;

public:
    CWH(string s, float r)
    {
        title = s;
        rating = r;
    }
    virtual void display() {}
};

class videoLectures : public CWH
{
    float videolen;

public:
    videoLectures(string s, float r, float vl) : CWH(s, r)
    {
        videolen = vl;
    }
    void display()
    {
        cout << "Video Title : " << title << endl
             << "Video Ratings : " << rating << " out of 5 " << endl
             << "Length : " << videolen << endl;
    }
};

class websiteLectures : public CWH
{
    int words;

public:
    websiteLectures(string s, float r, int wc) : CWH(s, r)
    {
        words = wc;
    }
    void display()
    {
        cout << "Website Page : " << title << endl
            << "Page Ratings : " << rating << " out of 5" << endl
             << "Words : " << words << endl;
    }
};
int main()
{
    string name = "C++ Tutorials";
    float rate = 4.3, duration = 15.23;
    int count = 514;

    videoLectures v1(name, rate, duration);
    v1.display();

    websiteLectures w1(name, rate, count);
    w1.display();

    CWH * base_ptr[2];
    base_ptr[0] = &v1;
    base_ptr[1] = &w1;

    base_ptr[0]->display();
    base_ptr[1]->display();
    return 0;
}
/*
    RULES FOR VIRTUAL FUNCTIONS

    1) They cannot be static
    2) They are only accessed by class pointer otherwise they have no use
    3) They can be present in a code without any use like the code above
    4) They can be a friend function for a class
    5) If a pointer doesn't find the function in a derived class, it will by default fetch the base class function as an alternative
        instead of throwing any error
*/