C# 2

1. partial class
partial class Circle
{
public Circle() //default construtor
{
this.radius = 0;
}

public Circle(int initialRadius) //overloaded construtor
{
this.radius = initialRadius;
}
}

//the contents of cir2.cs look like this
partial class Circle
{
private int radius;
public double Area()
{
return Math.PI * this.radius * this.radius;
}
}