C++ 实验八虚函数和抽象类

一、要求

编写一个程序计算三角形、正方形、圆的面积,要求抽象出一个基类 CBase ,在抽象类中设计两个纯虚函数,分别用来求面积和周长

二、分析

由要求分析可知，在Cbase类中声明纯虚函数，之后在Triangle类、Cube类、Circle类分别对两个函数重写，在main函数中通过指针调用

C++实验15

三、代码

💻提示：所有实验源码已在github整理

#include<iostream>
using namespace std;
#define PI 3.1415926

class CBase
{
public:
	virtual void area() = 0;
	virtual void circum() = 0;
};

class Triangle :public CBase
{
public:
	Triangle(double d, double h, double a, double b, double c)
	{
		this->d = d;
		this->h = h;
		this->a = a;
		this->b = b;
		this->c = c;
	}
	void area()
	{
		cout << "三角形的面积为" << d * h/2 << endl;
	}
	void circum()
	{
		cout << "三角形的周长为" << a + b + c << endl;
	}
private:
	double d;
	double h;
	double a;//定义三条边a,b,c
	double b;
	double c;
};

class Cube :public CBase
{
public:
	Cube(double c)
	{
		this->c = c;
	}
	void area()
	{
		cout << "长方形的面积为" << c * c << endl;
	}
	void circum()
	{
		cout << "长方形的周长为" << 4 * c << endl;
	}
private:
	double c;
};

class Circle :public CBase
{
public:
	Circle(double r)
	{
		this->r = r;
	}
	void area()
	{
		cout << "圆的面积为" << PI * r*r << endl;
	}
	void circum()
	{
		cout << "圆的周长为" << 2 * PI*r << endl;
	}
private:
	double r;
};
int main()
{
	CBase * t = new Triangle(3, 4, 3, 4, 5);
	t->area();
	t->circum();
	delete t;

	CBase * c = new Cube(1);
	c->area();
	c->circum();
	delete c;

	CBase * cir = new Circle(1);
	cir->area();
	cir->circum();
	delete cir;

	system("pause");
	return 0;
}