C++习题 虚函数-计算图形面积
Time Limit: 1 Sec Memory Limit: 128 MB
Submit: 122 Solved: 86
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Description
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。
Input
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
Output
所有图形面积之和（结果保留两位小数）
Sample Input
12.63.54.5 8.42.0 4.5 3.24.5 8.4
Sample Output
total of all areas=574.11
#include
#include
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<
>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="<