Question

6. define a C++ class having the following members: (1) 2 instance methods  the prototype of the first method is double funA(int r). The parameter r represents the radius of a circle. The funA will calculate the area of a circle and the value of its radius is from the parameter r. It will return the area of the circle.  the prototype of the second method is double funB(int w, int h). The parameters w and h represent the width and height of a rectangle. The funB will calculate the area of the rectangle and return the area of the rectangle. (2) 1 static method  the prototype of the static method is static int funC(int a1, int a2). The funC will calculate the sum of the parameters a1 and a2, and return the sum. (3) 1 static variable representing PI - the main method - in this method, it calls a default constructor to create an instance of this class. Then, call each instance method above. Finally, call the static method in the main method.

Answer 1

Program Plan: As per the question, i created Demo class which contains all the instance methods funA and funB also a static method funC. the static methods are independent from class object,they can execute before the class object created. the static method or variable can be accessed by using Scope resolution operator(::). in the class there is a static variable PI, which value is 3.1419.

Program:

#include<iostream.h>
#include<conio.h>
//Demo calss definition
class Demo
{ //private section where static variable declared
private:
static double PI;
//public section where member functions defined
public:
//constructor
Demo()
{
}
//funA returns area of the Circle
double funA(int r)
{
return(PI*r*r);
}
//funB returns the area of the rectangle
double funB(int w,int h)
{
return(w*h);
}
//return the sun of the parameters
static int funC(int a1,int a2)
{
return(a1+a2);
}
};
//End of Demo class
//Assigning the value to static variable
double Demo::PI = 3.1419;
//main method definition
void main()
{
Demo d;
int r,i,j,w,h;
clrscr();
cout<<"Enter radius of the circle:";
cin>>r;
cout<<"\nArea of the circle:"<<d.funA(r);
cout<<"\nenter height and Width: ";A
cin>>h>>w;
cout<<"\nArea of the Rectangle:" <<d.funB(w,h);
cout<<"\nEnter values for i and j:";
cin>>i>>j;
//static method calling.static method need not be called with class object.
//so class name can be used to call the function
cout<<"\nstatic method call:"<<Demo::funC(i,j);
getch();
}

Sample Output: