program to show the basics of inline function in oops

#include<iostream.h>
#include<conio.h>
class rectangle
{
 int a,b;
 public:
       void setdata(int x,int y)
       {
    a=x;
    b=y;
    }
    void show()
    {
    cout<<"area of rectangle is "<<a*b;
    }
};
void main()
{
 clrscr();
 rectangle r1,r2,r3;
 r1.setdata(7,6);
 r1.show();
 cout<<endl;
 r1.setdata(5,5);
 r2.setdata(10,10);
 r2.show();
 cout<<endl;
 r1.show();
 getch();
 }

program to find the area and circumference of circle using classes

#include<iostream.h>
#include<conio.h>
class circle
{
 float r;
 public:
 void setdata();
 void area();
 void circum();
 };
 void circle::setdata()
 {cout<<"enter the radius of circle  ";
  cin>>r;
 }
 void circle::area()
 {  double area;
    area=3.14*r*r;
    cout<<"area of circle "<<area<<endl;
  }
 void circle::circum()
 {  double cir;
    cir=2*3.14*r;
    cout<<"circumference of circle is "<<cir<<endl;
  }
  void main()
  { clrscr();
   circle c1,c2;
    c1.setdata();
    cout<<"for first circle"<<endl;
    c1.area();
    c1.circum();
    cout<<"for second circle"<<endl;
    c2.setdata();
    c2.area();
    c2.circum();
    getch();
    }

program to add, sub, mul ,and divide two complex numbers using classes

#include<iostream.h>
#include<conio.h>
class complex
{
 double a,b,c,d;
 public:
 void setdata();
 void add();
 void subt();
 void mult();
 void divd();
 };
 double x,y;
 void complex::setdata()
 {
  cout<<"for first number"<<endl;
  cout<<"enter real part ";
  cin>>a;
  cout<< "enter imiginary part ";
  cin>>b;
  cout<<endl;
  cout<<"for second number"<<endl;
  cout<<"enter real part ";
  cin>>c;
  cout<<"enter imiginary part ";
  cin>>d;
  cout<<endl;
  }
  void complex::add()
  {
   x=a+c;
   y=b+d;
   cout<<"addition of complex number is "<<x<<"  "<<y<<"i"<<endl;
   }
  void complex::subt()
  {
    x=a-c;
    y=b-d;
    cout<<"subtraction of complel number is "<<x<<"  "<<y<<"i"<<endl;
   }
  void complex::mult()
   {
    x=(a*c)-(b*d);
    y=(b*c)+(a*d);
    cout<<"multiple of complex number is "<<x<<"  "<<y<<"i"<<endl;
    }
   void complex::divd()
   {
    x=((a*c)+(b*d))/((c*c)+(d*d));
    y=((b*c)-(a*d))/((c*c)+(d*d));
    cout<<"divident number is "<<x<<"  "<<y<<"i"<<endl;
    }
  void main()
  {
   clrscr();
   complex c1;
   c1.setdata();
   c1.add();
   c1.subt();
   c1.mult();
   c1.divd();
   getch();
   }