C++習題 虛函數-計算圖形面積

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C++習題 虛函數-計算圖形面積Time Limit: 1 Sec  Memory Limit: 128 MB
Submit: 122  Solved: 86
[Submit][Status][Web Board]Description編寫一個程式，定義抽象基類Shape，由它派生出5個衍生類別： Circle(圓形)、Square(正方形)、Rectangle(矩形)、Trapezoid(梯形)、Triangle(三角形)。用虛函數分別計算幾種圖形面積，並求它們之和。要求用基類指標數組，使它每個元素指向一個衍生類別對象。 

Input圓的半徑正方形的邊長矩形的邊長梯形的上底和下底，高三角形的底與高

Output

全部圖形面積之和（結果保留兩位小數）

Sample Input12.63.54.5 8.42.0 4.5 3.24.5 8.4Sample Outputtotal of all areas=574.11

#include <iostream>#include<iomanip>using namespace std;class Shape{  public:      virtual float area()=0;      private:};class Circle:public Shape{public:    Circle(float s)    {r=s;    }float area(){return (3.1415926*r*r);}    private:        float r;};class Square:public Shape{public:    Square (float s)    {     a=s;    }    float area() { return (a*a); }private:    float a;};class Rectangle :public Shape{public:    Rectangle (float s,float d)    {     a=s;     b=d;    } float area() { return (a*b);}private:    float a,b;};class Trapezoid:public Shape{public:    Trapezoid (float s,float d,float ss)    {     w1=s;     w2=d;     h=ss;    }    float area() { return ((w1+w2)*h/2); }private:    float w1,w2,h;};class Triangle:public Shape{public:    Triangle (float s,float d)    {     w=s;     h=d;    }    float area() { return (w*h/2); }private:    float w,h;};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;}

C++習題 虛函數-計算圖形面積