定义一个基类shape，再次基础上派生出 长方形，正方形，圆形，二者都有getArea()计算对象的面积

Posted 2021-10-20 Roam-G

定义一个基类shape，再次基础上派生出 长方形，正方形，圆形，二者都有getArea()计算对象的面积

#include <iostream>
using namespace std;

//基类 shape
class Shape {
public:
	Shape() {}
	~Shape() {}
	virtual float getArea() {
		return -1;
	}
};

//派生类 圆形
class Circle :public Shape {
public:
	Circle(float radius):itsRadius(radius){}
	~Circle(){}
	float getArea() {
		return 3.14 * itsRadius * itsRadius;
	}
private:
	float itsRadius;
};


//派生类 长方形
class Rectangle :public Shape {
public:
	Rectangle(float len, float width) :itsLength(len), itsWidth(width) {};
	~Rectangle(){}
	virtual float getArea() {
		return itsLength * itsWidth;
	}
	virtual float getLength() {
		return itsLength;
	}
	virtual float getWidth() {
		return itsWidth;
	}
private:
	float itsWidth;
	float itsLength;
};

//正方形
class Square :public Rectangle {
public: 
	Square(float len);
	~Square() {}
};

Square::Square(float len) :Rectangle(len, len) {

}

int main() {
	Shape* sp;

	sp = new Circle(5);
	cout << "圆形的面积：" << sp->getArea() << endl;
	delete sp;
	sp = new Rectangle(4, 6);
	cout << "长方形的面积：" << sp->getArea() << endl;
	delete sp;
	sp = new Square(5);
	cout << "正方形的面积：" << sp->getArea() << endl;
	delete sp;
	return 0;
}