JanWan I'm currently working on this question...

Samath Check this out.

JanWan The interface for this question (Circle.h)
class Circle

JanWan #include <iostream>
#include <cmath>

using namespace std;


class Circle
{
      private: //Private member
              double radius; //Declare variable
              
      public: //Public data members
             void setRadius(double); //Mutator
             double getRadius(); //Accessor
             
             //Other member function
             double getArea();
             double getDiameter();
             double getCircumference();
            
             //Constructors
             Circle(double);
             Circle();
};

JanWan This is the implementation of the circle
Circle.cpp

JanWan #include <cstdlib>
#include <iostream>
#include <cmath>
#include "Circle.h"
#include <stdexcept>
#include "ZeroException.h"


using namespace std;

const double pi = 3.14159;

//Radius function/ Mutator
void Circle::setRadius(double R)
{
     //Throw exception if radius is 0
     if(R == 0.0)
     {
               throw ZeroException(); //Throw an exception
     }
     
     radius = R; //set R value to variable radius
}

//Radius function/ Accessor
double Circle::getRadius()
{
     return radius; //return value of radius
}

//Area function
double Circle::getArea()
{
       double area; //Declare variable
       return area = pi * radius * radius; //calculation of area
}

//Diameter function
double Circle::getDiameter()
{
       double dia; //Declare variable
       return dia = radius * 2; //calculate and return diameter
}

//Circumference function
double Circle::getCircumference()
{
       double CirF; //Declare variable
       return CirF = 2 * pi * radius; //Calculate and return the circumference
}

//Constructor with argument
Circle::Circle(double R)
{
     setRadius(R); //set variable in constructor
}

//Default constructor
Circle::Circle()
{
      radius = 1.0; //set radius to 1.0
}

J.W. PRODUCTION

JanWan Main/Tester for the program

JanWan #include <cstdlib>
#include <iostream>
#include <cmath>
#include "Circle.h"
#include "ZeroException.h"

using namespace std;

int main(int argc, char *argv[])
{
    double rad; //Declare variable
    
    cout<<"Enter the circle radius: ";
    
    //Try contain code that might cause exception and code that
    //should not execute if exception occur
    try
    {
       cin>>rad; //input value
       Circle cork(rad); //instant of the class
       cout<<endl;
       
       //Display result
       cout<<"Radius: \t\t "<<cork.getRadius()<<endl;
       cout<<"Area of circle: \t "<<cork.getArea()<<endl;
       cout<<"Diameter of circle: \t "<<cork.getDiameter()<<endl;
       cout<<"Circumference of circle: "<<cork.getCircumference()<<endl;
       cout<<endl;
    }
    //ZeroException handles by Exception Handler
    catch(ZeroException &Zero) //catch an exception
    {   
              cout<<"Exception occured: "<<Zero.what()<<endl;
              cout<<endl;
    }
    
    system("PAUSE");
    return 0;
}

JanWan Screen Shot for Class Circle Program

Enter the value radius


Results of Radius


Error message from Exception Handling
Zero can not be enter as a valid value


Enjoy yourself until next time....

J.W. PRODUCTION

Samath repect