/*This program will demonstrate inheritance. A quadratic function (yes, you have to remember

your algebra) in the form y = ax^2 + bx + c will inherit the bx + c from a linear function

this is similar to composition of classes, which was covered in chapter 7

We say the class that inherits from another is a "derived" class, and the one that gets

inherited is the "base" class. This means the derived class inherits from the base class

As you will see, the variables and functions of the base class are imported into the derived class.*/

#include<iostream>

using namespace std;

class Linear /*will make a function in the form y = mx + b*/

{

public:

Linear(float=1, float=0);

void printLine();

protected: /*like private (no access from main), but can be accessed by derived classes*/

float slope; /*the coefficient of x*/

float constant; /*the value in the equation that doesn't have a variable*/

};

Linear::Linear(float m, float b)

{

slope=m;

constant=b;

}

void Linear::printLine()

{

cout<<"y = "<<slope<<"x + "<<constant<<endl;

}

class Quad: public Linear /*inherits the bx + c from the Linear class*/

{

public:

Quad(float=1, float=1, float=0);

void print();

private:

float degree; /*the a in ax^2*/

};

Quad::Quad(float a, float b, float c)

:Linear(b,c) /*makes a call to the base class Linear constructor from the derived class Quad constructor to assign b and c*/

{

degree=a;

}

void Quad::print()

{

/*Quad functions can access the protected members of Linear because of the inheritance, but the main and other classes can not.*/

cout<<"y = "<<degree<<"x^2 + "<<slope<<"x + "<<constant<<endl;

}

main()

{

Linear line(4,2); /*base classes can still be used in the main, not only in derived*/

line.printLine(); /*classes, but they don't have to be in the main at all*/

Quad func(5,2,9);

func.print(); /*you can use both the functions in the public part of the derived*/

func.printLine(); /*class, and in the public part of the base class*/

return 0;

}