Function Overloading in C++

//Function Overloading
#include<iostream.h>
#include<stdlib.h>
#include<conio.h>
#define pi 3.14
class fn
{
public:
 void area(int); //circle
 void area(int,int); //rectangle
 void area(float ,int,int);  //triangle
};

void fn::area(int a)
{
 cout<<"Area of Circle:"<<pi*a*a;
}
void fn::area(int a,int b)
{
 cout<<"Area of rectangle:"<<a*b;
}
void fn::area(float t,int a,int b)
{
 cout<<"Area of triangle:"<<t*a*b;
}

void main()
{
 int ch;
 int a,b,r;
 //clrscr();
 fn obj;
 cout<<"\n\t\tFunction Overloading";
 cout<<"\n1.Area of Circle"<<endl;
 cout<<"\n2.Area of Rectangle"<<endl;
 cout<<"\n3.Area of Triangle"<<endl;
 cout<<"\n4.Exit\n";
 cout<<"Enter your Choice:";
 cin>>ch;
 switch(ch)
 {
  case 1:
  cout<<"Enter Radious of the Circle:";
  cin>>r;
  obj.area(r);
  break;
  case 2:
  cout<<"Enter Sides of the Rectangle:";
  cin>>a>>b;
  obj.area(a,b);
  break;
  case 3:
  cout<<"Enter Sides of the Triangle:";
  cin>>a>>b;
  obj.area(0.5,a,b);
  break;
  case 4:
  exit(0);
 }
getch();
}