C++习题 虚函数-计算图形面积
时间: 1ms 内存:128M
描述:
编写一个程序,定义抽象基类Shape,由它派生出5个派生类: Circle(圆形)、Square(正方形)、Rectangle(矩形)、Trapezoid(梯形)、Triangle(三角形)。用虚函数分别计算几种图形面积,并求它们之和。要求用基类指针数组,使它每一个元素指向一个派生类对象。
输入:
圆的半径正方形的边长矩形的边长梯形的上底和下底,高三角形的底与高
输出:
所有图形面积之和(结果保留两位小数)
示例输入:
12.6
3.5
4.5 8.4
2.0 4.5 3.2
4.5 8.4
示例输出:
total of all areas=574.11
提示:
参考答案(内存最优[1268]):
#include <iostream>
#include <iomanip>
using namespace std;
//定义抽象基类Shape
class Shape
{
public:
virtual double area() const =0; //纯虚函数
};
//定义Circle(圆形)类
class Circle:public Shape
{
public:
Circle(double r):radius(r) {} //结构函数
virtual double area() const
{
return 3.14159*radius*radius;
}; //定义虚函数
protected:
double radius; //半径
};
//定义Square(正方形)类
class Square:public Shape
{
public:
Square(double s):side(s) {} //结构函数
virtual double area() const
{
return side*side; //定义虚函数
}
protected:
double side;
};
//定义Rectangle(矩形)类
class Rectangle:public Shape
{
public:
Rectangle(double w,double h):width(w),height(h) {} //结构函数
virtual double area() const
{
return width*height; //定义虚函数
}
protected:
double width,height; //宽与高
};
//定义Trapezoid(梯形)类
class Trapezoid:public Shape
{
public:
Trapezoid(double t,double b,double h):top(t),bottom(t),height(h) {} //结构函数
virtual double area() const
{
return 0.5*(top+bottom)*height; //定义虚函数
}
protected:
double top,bottom,height; //上底、下底与高
};
//定义Triangle(三角形)类
class Triangle:public Shape
{
public:
Triangle(double w,double h):width(w),height(h) {} //结构函数
virtual double area() const
{
return 0.5*width*height; //定义虚函数
}
protected:
double width,height; //宽与高
};
int main()
{
float r,a,b,w1,w2,w,h;
cout<<fixed<<setprecision(2);
cin>>r;
Circle circle(r);
cin>>a;
Square square(a);
cin>>a>>b;
Rectangle rectangle(a,b);
cin>>w1>>w2>>h;
Trapezoid trapezoid(w1,w1,h);
cin>>w>>h;
Triangle triangle(w,h);
Shape *pt[5]= {&circle,&square,&rectangle,&trapezoid,&triangle};
double areas=0.0;
for(int i=0; i<5; i++)
areas=areas+pt[i]->area();
cout<<"total of all areas="<<areas<<endl;
return 0;
}
参考答案(时间最优[0]):
#include <iostream>
#include <iomanip>
using namespace std;
//定义抽象基类Shape
class Shape
{
public:
virtual double area() const =0; //纯虚函数
};
//定义Circle(圆形)类
class Circle:public Shape
{
public:
Circle(double r):radius(r) {} //结构函数
virtual double area() const
{
return 3.14159*radius*radius;
}; //定义虚函数
protected:
double radius; //半径
};
//定义Square(正方形)类
class Square:public Shape
{
public:
Square(double s):side(s) {} //结构函数
virtual double area() const
{
return side*side; //定义虚函数
}
protected:
double side;
};
//定义Rectangle(矩形)类
class Rectangle:public Shape
{
public:
Rectangle(double w,double h):width(w),height(h) {} //结构函数
virtual double area() const
{
return width*height; //定义虚函数
}
protected:
double width,height; //宽与高
};
//定义Trapezoid(梯形)类
class Trapezoid:public Shape
{
public:
Trapezoid(double t,double b,double h):top(t),bottom(t),height(h) {} //结构函数
virtual double area() const
{
return 0.5*(top+bottom)*height; //定义虚函数
}
protected:
double top,bottom,height; //上底、下底与高
};
//定义Triangle(三角形)类
class Triangle:public Shape
{
public:
Triangle(double w,double h):width(w),height(h) {} //结构函数
virtual double area() const
{
return 0.5*width*height; //定义虚函数
}
protected:
double width,height; //宽与高
};
int main()
{
float r,a,b,w1,w2,w,h;
cout<<fixed<<setprecision(2);
cin>>r;
Circle circle(r);
cin>>a;
Square square(a);
cin>>a>>b;
Rectangle rectangle(a,b);
cin>>w1>>w2>>h;
Trapezoid trapezoid(w1,w1,h);
cin>>w>>h;
Triangle triangle(w,h);
Shape *pt[5]= {&circle,&square,&rectangle,&trapezoid,&triangle};
double areas=0.0;
for(int i=0; i<5; i++)
areas=areas+pt[i]->area();
cout<<"total of all areas="<<areas<<endl;
return 0;
}
题目和答案均来自于互联网,仅供参考,如有问题请联系管理员修改或删除。