This chapter uses the class rectangleType to illustate how to overload the operators +, *, ==, !=, >>, and <<. In this exercise, first redefine the class rectangleType by declaring the instance variables as protected and then overload additional operators as defined in parts 1 to 3.

1. Overload the pre- and post-increment and decrement operators to increment and decrement, respectively, the length and width of a rectangle by one unit. (Note that after decrementing the length and width, they must be postive.)

2. Overload the binary operator - to subtract the dimensions of one rectangle from the corresponding dimensions of another rectangle. If the resulting dimensions are not positive, output an appropriate message and do not perform the operation.

3. The operators == and != are overloaded by considering the lengths and widths of rectangles. Redefine the functions to overload the relational operator by considering the areas of rectangles as follows: Two rectangles are the same, if they have the same area; otherwise, the rectangles are not the same. Similary, rectangle yard1 is greater than rectangle yard2 if the area of yard1 is greater than the area of yard2. Overload the remaining relational operators using similar definitions.

4. Write the definitions of the functions to overload the operators defined in parts a to c.

5. Write a test program that tests various operations on the class rectangleType.

class rectangleType {

Check the attached image for code screenshot and output.

Explanation:

#######################################

      Rectangle.cpp

#######################################

#include "Rectangle.h"

Rectangle::Rectangle() {

       length = 0;

       width = 0;

}

Rectangle::Rectangle(double newLength, double newWidth) {

       length = newLength;

       width = newWidth;

}

void Rectangle::setLength(double l) {

       length = l;

}

void Rectangle::setWidth(double w) {

       width = w;

}

double Rectangle::getLength() {

       return length;

}

double Rectangle::getWidth() {

       return width;

}

double Rectangle::computeArea() {

       return length * width;

}

double Rectangle::computePerimeter() {

       return 2 * (length + width);

}

Rectangle Rectangle::operator++ () {

       length++;

       width++;

       return *this;

}

Rectangle Rectangle::operator++ (int) {

       Rectangle r(length, width);

       ++length;

       ++width;

       return r;

}

Rectangle Rectangle::operator-- () {

       if(length > 0) {

               length--;

       }

       if(width > 0) {

               width--;

       }

       return *this;

}

Rectangle Rectangle::operator-- (int) {

       Rectangle r(length, width);

       if(length > 0) {

               length--;

       }

       if(width > 0) {

               width--;

       }

       return r;

}

Rectangle Rectangle::operator- (Rectangle other) {

       if(length > other.length && width > other.width) {

               length--;

               width--;

       } else {

               cout << "invalid operation. Subtrated Rectangle is bigger" << endl;

       }

       return *this;

}

bool Rectangle::operator==(Rectangle other) {

       return (length == other.length) && (width == other.width);

}

bool Rectangle::operator!=(Rectangle other) {

       return (length != other.length) || (width != other.width);

}

void Rectangle::printDetails() {

       cout << "Rectangle Report" << endl;

       cout << "Dimensions: " << length << " X " << width << endl;

       cout << "Area: " << computeArea() << endl;

       cout << "Perimeter: " << computePerimeter() << endl;

       cout << "********************" << endl;

}

#######################################

        Rectangle.h

#######################################

#include<iostream>

#include<iomanip>

using namespace std;

class Rectangle {

       double length, width;

       public:

       Rectangle();

       Rectangle(double newLength, double newWidth);

       void setLength(double l);

       void setWidth(double w);

       double getLength();

       double getWidth();

       double computeArea();

       double computePerimeter();

       Rectangle operator++ ();

       Rectangle operator++ (int);

       Rectangle operator-- ();

       Rectangle operator-- (int);

       Rectangle operator- (Rectangle r);

       bool operator== (Rectangle r);

       bool operator!= (Rectangle r);

       void printDetails();

};

#######################################

           main.cpp

#######################################

#include "Rectangle.h"

       // Ask the user to type in a length and width and

       // create an object called rect2 of the rectangle class

       // See output for format

       cout << "Enter the length of rectangle 3: ";

       cin >> l;

       cout << "Enter the width of rectangle 3: ";

       cin >> w;

       Rectangle rect3(l, w);

       cout << endl;

       cout.setf(ios::fixed);

       cout.precision(1);

       // Using the member function in the class, print rect1, rect2,

       // and rect3 details in that order

       rect1.printDetails();

       rect2.printDetails();

       rect3.printDetails();

       cout << endl;

       // Print each rectangle in the format shown on the output

       cout << "Rectangle 1: " << rect1.getLength() << " X " << rect1.getWidth() << endl;

       cout << "Area: " << rect1.computeArea() << " Perimeter: " << rect1.computePerimeter() << endl;

       cout << "Rectangle 2: " << rect2.getLength() << " X " << rect2.getWidth() << endl;

       cout << "Area: " << rect2.computeArea() << " Perimeter: " << rect2.computePerimeter() << endl;

       cout << "Rectangle 3: " << rect3.getLength() << " X " << rect3.getWidth() << endl;

       cout << "Area: " << rect3.computeArea() << " Perimeter: " << rect3.computePerimeter() << endl;

       if(rect2 == rect3) {

               cout << "rectangle 2 and 3 are same." << endl;

       } else {

               cout << "rectangle 2 and 3 are not same." << endl;

       }

       cout << "After incrementing rectangle 2: ";

       rect2++;

       rect2.printDetails();

   return 0;

}