每日打卡-14

一.问题描述

  请编写一个抽象类Shape，在此基础上派生出类Rectangle和Circle，二者都有计算对象面积的函数getArea()、计算对象周长的函数getPerim()。

  在此基础上，通过继承Rectangle 得到一个新的类 Square，然后在 Shape 中增加一个函数int getVertexCount() const用来获得当前图形的顶点个数，用以下几种方法分别实现，并体会各自的优劣。

(1)使用dynamic_cast 实现 Shape::getVertexCount函数。

(2)使用typeid 实现Shape::getVertexCount 函数。

(3)将Shape::getVertexCount声明为纯虚函数,在派生类中给出具体实现。

二.设计思路

  按照题目要求编写程序即可。

三.流程图

四.伪代码 

1

五.代码实现 

（1）

#include<iostream>
using namespace std;
#define PI 3.14
class shape {
public:
	virtual void setvalues() = 0;
	virtual float area() = 0;
	virtual float perim() = 0;
	int getVertexCount() const;
};

class rectangle :public shape {
protected:
	float wide, high;
public:
	virtual void setvalues() {
		cin >> wide >> high;
		if (wide < 0 || high < 0) {
			cout << "Set Value Error!" << endl;
			_exit(0);
		}
	}
	virtual float area() {
		float Area = wide * high;
		return Area;
	}
	virtual float perim() {
		float Perim = (wide + high) * 2;
		return Perim;
	}
	
};

class square :public rectangle {
public:
	void setvalues() {
		cin >> wide;
		if (wide < 0 ) {
			cout << "Set Value Error!" << endl;
			_exit(0);
		}
	}
	float area() {
		float Area = wide * wide;
		return Area;
	}
	float perim() {
		float Perim = wide * 4;
		return Perim;
	}
	
};
class circle :public shape {
private:
	float r;
public:
	void setvalues() {
		cin >> r;
		if (r < 0) {
			cout << "Set Value Error!" << endl;
			_exit(0);
		}
	}
	float area() {
		float Area = r * r * PI;
		return Area;
	}
	float perim() {
		float Perim = 2 * PI * r;
		return Perim;
	}
	
};

int shape::getVertexCount() const {
	if (dynamic_cast<circle*>(const_cast<shape*>(this)) != 0)
		return 0;
	else if (dynamic_cast<rectangle*>(const_cast<shape*>(this)) != 0 || dynamic_cast<square*>(const_cast<shape*>(this)) != 0)
		return 4;
	else
		return -1;
}
int main() {
	rectangle a;
	square b;
	circle d;
	shape* p;
	p = &a;
	p->setvalues();
	cout << p->area() << endl;
	cout << p->perim() << endl;
	cout << p->getVertexCount() << endl << endl;

	p = &b;
	p->setvalues();
	cout << p->area() << endl;
	cout << p->perim() << endl;
	cout << p->getVertexCount() << endl << endl;

	p = &d;
	p->setvalues();
	cout << p->area() << endl;
	cout << p->perim() << endl;
	cout << p->getVertexCount() << endl << endl;
	return 0;

}

（2）

#include<iostream>
using namespace std;
#define PI 3.14
class shape {
public:
	virtual void setvalues() = 0;
	virtual float area() = 0;
	virtual float perim() = 0;
	int getVertexCount() const;
};

class rectangle :public shape {
protected:
	float wide, high;
public:
	virtual void setvalues() {
		cin >> wide >> high;
		if (wide < 0 || high < 0) {
			cout << "Set Value Error!" << endl;
			_exit(0);
		}
	}
	virtual float area() {
		float Area = wide * high;
		return Area;
	}
	virtual float perim() {
		float Perim = (wide + high) * 2;
		return Perim;
	}
	
};

class square :public rectangle {
public:
	void setvalues() {
		cin >> wide;
		if (wide < 0 ) {
			cout << "Set Value Error!" << endl;
			_exit(0);
		}
	}
	float area() {
		float Area = wide * wide;
		return Area;
	}
	float perim() {
		float Perim = wide * 4;
		return Perim;
	}
	
};
class circle :public shape {
private:
	float r;
public:
	void setvalues() {
		cin >> r;
		if (r < 0) {
			cout << "Set Value Error!" << endl;
			_exit(0);
		}
	}
	float area() {
		float Area = r * r * PI;
		return Area;
	}
	float perim() {
		float Perim = 2 * PI * r;
		return Perim;
	}
	
};

int shape::getVertexCount() const {
	const type_info& info = typeid(*this);
	if (info == typeid(circle))
		return 0;
	else if (info == typeid(rectangle) || info == typeid(square))
		return 4;
	else
		return -1;
}
int main() {
	rectangle a;
	square b;
	circle d;
	shape* p;
	p = &a;
	p->setvalues();
	cout << p->area() << endl;
	cout << p->perim() << endl;
	cout << p->getVertexCount() << endl << endl;

	p = &b;
	p->setvalues();
	cout << p->area() << endl;
	cout << p->perim() << endl;
	cout << p->getVertexCount() << endl << endl;

	p = &d;
	p->setvalues();
	cout << p->area() << endl;
	cout << p->perim() << endl;
	cout << p->getVertexCount() << endl << endl;
	return 0;

}

（3）

#include<iostream>
using namespace std;
#define PI 3.14
class shape {
public:
	virtual void setvalues() = 0;
	virtual float area() = 0;
	virtual float perim() = 0;
	virtual int getVertexCount() const = 0;
};
class rectangle :public shape {
protected:
	float wide, high;
public:
	void setvalues() {
		cin >> wide >> high;
		if (wide < 0 || high < 0) {
			cout << "Set Value Error!" << endl;
			_exit(0);
		}
	}
	float area() {
		float Area = wide * high;
		return Area;
	}
	float perim() {
		float Perim = (wide + high) * 2;
		return Perim;
	}
	int getVertexCount() const{
		return 4;
	}
};

class square :public rectangle {
public:
	void setvalues() {
		cin >> wide;
		if (wide < 0 ) {
			cout << "Set Value Error!" << endl;
			_exit(0);
		}
	}
	float area() {
		float Area = wide * wide;
		return Area;
	}
	float perim() {
		float Perim = wide * 4;
		return Perim;
	}
	int getVertexCount() const {
		return 4;
	}
};
class circle :public shape {
private:
	float r;
public:
	void setvalues() {
		cin >> r;
		if (r < 0) {
			cout << "Set Value Error!" << endl;
			_exit(0);
		}
	}
	float area() {
		float Area = r * r * PI;
		return Area;
	}
	float perim() {
		float Perim = 2 * PI * r;
		return Perim;
	}
	int getVertexCount() const{
		return 0;
	}
};
int main() {
	rectangle a;
	square b;
	circle d;
	shape* p;
	p = &a;
	p->setvalues();
	cout << p->area() << endl;
	cout << p->perim() << endl;
	cout << p->getVertexCount() << endl;

	p = &b;
	p->setvalues();
	cout << p->area() << endl;
	cout << p->perim() << endl;
	cout << p->getVertexCount() << endl;

	p = &d;
	p->setvalues();
	cout << p->area() << endl;
	cout << p->perim() << endl;
	cout << p->getVertexCount() << endl;
	return 0;

}