C++ 7_5

 1 #include<iostream>
 2 using namespace std;
 3 const double PI=3.14;
 4
 5 class Shape
 6 {
 7 public:
 8     Shape (float a,float b=0.0){this->a=a;this->b=b;}
 9 protected:
10     float a,b;
11 };
12
13 class Rectangle:public Shape
14 {
15 public:
16     Rectangle(float l,float w):Shape(l,w){}
17     float getArea(){return a*b;}
18 };
19
20 class Circle:public Shape
21 {
22 public:
23     Circle(float r):Shape(r){}
24     float getArea(){return a*a*PI;}
25 };
26
27 class Square:public Rectangle
28 {
29 public:
30     Square(float l):Rectangle(l,l){}
31     float getArea(){return a*a;}
32 };
33
34
35 int main()
36 {
37     Rectangle R(3,4);
38     Circle C(5);
39     Square S(5);
40     cout<<"The Rectangle area is "<<R.getArea()<<endl;
41     cout<<"The Circle area is "<<C.getArea()<<endl;
42     cout<<"The Square area is "<<S.getArea()<<endl;
43     return 0;
44 }