클래스 Circle(면적 구하기)

1.

#include <iostream>
using namespace std;

class Circle {
	int radius;
public:
	Circle() { radius = 1; }
	Circle(int r) { radius = r; }
	void setRadius(int r) { radius = r; }
	double getArea();
};

double Circle::getArea() {
	return 3.14*radius*radius;
}


int main() {
	Circle circles[2][3]; 									

	circles[0][0].setRadius(1);
	circles[0][1].setRadius(2);
	circles[0][2].setRadius(3);
	circles[1][0].setRadius(4);
	circles[1][1].setRadius(5);
	circles[1][2].setRadius(6);

	for(int i=0;i<2;i++)
		for (int j = 0; j < 3; j++) {
			cout << "Circle [" << i << "," << j << "]의 면적은 ";
			cout << circles[i][j].getArea() << endl;
		}
	
}

2.

#include <iostream>
using namespace std;

class Circle {
	int radius;
public:
	Circle() { radius = 1; }
	Circle(int r) { radius = r; }
	void setRadius(int r) { radius = r; }
	double getArea();
};

double Circle::getArea() {
	return 3.14*radius*radius;
}


int main() {

	Circle circles[2][3] = { {Circle(1),Circle(2),Circle(3)},{Circle(4),Circle(5),Circle(6)} };

	for (int i = 0; i < 2; i++)
		for (int j = 0; j < 3; j++) {
			cout << "Circle [" << i << "," << j << "]의 면적은 ";
			cout << circles[i][j].getArea() << endl;
		}

}

3.

#include<iostream>
using namespace std;

class Circle {
	int radius;
public:
	Circle() { radius = 1; }
	Circle(int radius) { this->radius = radius; }
	void setRadius(int radius) { this->radius = radius; }
	double getArea() { return 3.14*radius*radius; }
};

void readRadius(Circle &c) {
	int r;
	cout << "반지름을 입력하시오 : ";
	cin >> r;
	c.setRadius(r);

}

int main() {
	Circle donut;
	readRadius(donut);
	cout << "donut 의 면적 = " << donut.getArea() << endl;
}

4.

#include <iostream>
using namespace std;

class Circle {
	int radius;
public:
	Circle() { radius = 1; }
	Circle(int radius) { this->radius = radius; }
	~Circle() { cout << getArea() << endl; }
	void setRadius(int radius) { this->radius = radius; }
	double getArea() { return 3.14*radius*radius; }
};

Circle getCircle(int r) {
	Circle tmp(r);
	return tmp;
}

int main() {
	int r;
	Circle c;
	cout << c.getArea() << endl;

	cout << "반지름을 입력하세요 >>";
	cin >> r;

	c = getCircle(r);
}