• A constructor can all another constructor of the same class

//Rectangle.h
#ifndef RECTANGLE_H
#define RECTANGLE_H
class Rectangle
{
	private:
		double width;
		double length;
	public:
		//constructor
		Rectangle():Rectangle(0, 0){}
		Rectangle(double w):Rectangle(w, 2*w){}
		Rectangle(double w, double l):width(w), length(l){}

		//accessor
		double getWidth() const {return width;}
		double getLength() const {return length;}
		double getArea() const {return width*length;}

		//mutator
		void setWidth(double w) {width = w;}
		void setLength(double l) {length = l;}
};
#endif

//main.cpp
#include <iostream>
#include "Rectangle.h"

int main(int argc, char *argv[])
{
	Rectangle r(10);

	std::cout<<r.getArea()<<std::endl;

	return 0;
}
		

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