11.15 Controlled Access to Private Hardware Drivers

#include "Rectangle.h"

Rectangle::Rectangle() {
	length = 1;
	width = 1;
}

Rectangle::Rectangle(double length, double width) {
	this->length = length;
	this->width = width;
}

double Rectangle::getLength() const {
	return length;
}

double Rectangle::getWidth() const {
	return width;
}

void Rectangle::setLength(double length) {
	this->length = length;
}

void Rectangle::setWidth(double width) {
	this->width = width;
}

double Rectangle::area() const {
	return length * width;
}

double Rectangle::perimeter() const {
	return 2 * (length + width);
}

#ifndef RECTANGLE_HELPER_H
#define RECTANGLE_HELPER_H

#include "Rectangle.h"

class RectangleHelper {
	public:
		void modifyRectangle(Rectangle& rect) {
			rect.length = 500;
			rect.width = 500;
		}
};

#endif 

#include <iostream>
#include "Rectangle.h"
#include "RectangleHelper.h"

using namespace std;

void changeData(Rectangle& rect);
void printData(Rectangle& rect);

int main() {
	Rectangle r1(10, 25);
	RectangleHelper helper;

	cout << "r1 area: " << r1.area() << endl;

	changeData(r1);

	cout << "Now, r1 area: " << r1.area() << endl;

	helper.modifyRectangle(r1);
	cout << "after helper modifies, area: " << r1.area() << endl;

	cout << "printing data directly with printData:" << endl;
	printData(r1);

	return 0;
}

void changeData(Rectangle& rect) {
	rect.length = 100;
	rect.width = 100;
}

void printData(Rectangle& rect) {
	cout << "length: " << rect.length
		<< ", width: " << rect.width << endl;
}