圆柱，圆，正方，长方.cpp

这是用一个虚类派生来做的小程序

#include"iostream.h"
class basic
{
	int r;
public:
	
basic(int p)
{ 
    r=p;	  
}
  void banjing()
 {  
	cout<<"半径: "<<r;
	cout<<endl;
}
};
class yuan:public basic
{
int a,b;
public:
	yuan(int m,int n):basic(m)
	{
		b=n;
	}
	void mt()
	{
		double s,v;
		s=3.14*a*a*2+3.14*a*b;
		v=s*b;
		cout<<"(1)圆柱体的面积和体积："<<endl;
		basic::banjing();
		cout<<"高为："<<b<<endl;
		cout<<"面积："<<s<<endl;
		cout<<"体积："<<v<<endl;
}
};
class qiu:public basic
{
int c;
public:
	qiu(int p):basic(p)
	{
	c=p;
	}
	virtual void mt()
	{
		double s1,v1;
		s1=3.14*c*c*4;
		v1=(4*3.14*c*c*c)/3;
        cout<<"(2)球的面积和体积："<<endl;
		basic::banjing();
		cout<<"面积："<<s1<<endl;
		cout<<"体积："<<v1<<endl;
}
};




class basic1
{
public:
	int e;
	basic1(int f)
	{
		e=f;
	}
	void chang()
	{
	cout<<"长为:"<<e<<endl;
	}
void mt()
{
	int s3,v3;
	s3=6*e*e;
	v3=e*e*e;
	cout<<"(3)正方体的面积和体积:"<<endl;
	cout<<"面积："<<s3<<endl;
	cout<<"体积："<<v3<<endl;
}
};


class changfang:public basic1
{
public:
	int y,y1;
	changfang(int a1,int a2,int a3):basic1(a1)
	{
		y=a1;
		y1=a2;
	}
	void mt()
	{
		int s2,v2;
		s2=2*(e*y+e*y1+y*y1);
		v2=e*y*y1;
		cout<<"(4)长方体的面积和体积："<<endl;
        basic1::chang();
		cout<<"宽："<<y<<endl;
		cout<<"高："<<y1<<endl;
		cout<<"面积: "<<s2<<endl;
		cout<<"体积： "<<v2<<endl;
	}
};




void main()
{
	basic a(4);
	a.banjing();
	cout<<endl;
	yuan b(3,5);
	b.mt();
    cout<<endl<<endl;
	qiu c(5);
	c.mt();
    cout<<endl<<endl;
	basic1 d(6);
	d.chang();
	d.mt();
    cout<<endl<<endl;
    changfang e(2,4,6);
    e.mt();
}