#include
using namespace std;

class Circle
{
   private:
   double radius;
   double pi = 3.14159;
  
   public:

// constructors
   Circle()
   {
       radius = 0.0;
   }
   Circle(double radius)
   {
       this->radius = radius;
   }
   void setRadius(double radius)
   {
       this->radius = radius;
   }
   double getRadius()
   {
       return radius;
   }
   double getArea()
   {
       return pi*radius*radius;
   }
   double getDiameter()
   {
       return 2*radius;
   }
   double getCircumference()
   {
       return 2*pi*radius;
   }
};
  
int main() {
  
   Circle c;
   cout<<\"Calling·default·constructor:\";
   cout<<\"\nThe·circle's·radius·in·the·default·Circle·Object·is:\"<    cout<<\"\nCalling·setRadius(20)·to·change·radius·of·default:\";
   c.setRadius(20);
   cout<<\"\nThe·circle's·radius·in·the·default·Circle·Object·is·Now:\"<   

   cout<<\"\nCreating·Circle·circle2(10):\";
   Circle circle2(10);
      
   cout<<\"\nThe·circle2's·radius·in·the·circle2·Object·is:\"<    cout<<\"\nThe·circle2's·area·is·therefore:\"<    cout<<\"\nThe·circle2's·diameter·is·therefore:\"<    cout<<\"\nThe·circle2's·circumference·is·therefore:\"<   
  
   return 0;
}

Output:

Calling·default·constructor:
					The·circle's·radius·in·the·default·Circle·Object·is:0
					Calling·setRadius(20)·to·change·radius·of·default:
					The·circle's·radius·in·the·default·Circle·Object·is·Now:20
					Creating·Circle·circle2(10):
					The·circle2's·radius·in·the·circle2·Object·is:10
					The·circle2's·area·is·therefore:314.159
					The·circle2's·diameter·is·therefore:20
					The·circle2's·circumference·is·therefore:62.8318

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