main.cpp

this a good book.

#include<iostream.h>

/*****found*****/
#define double PI  3.1415

double area(double r=0)
{
	return PI*r*r;
}
/*****found*****/
double area(double a,double b=0)
{
	/*****found*****/
	return ab;
}
void main()
{
	cout<<"Area of point is "<<area(10)<<endl;
	cout<<"Area of point is "<<area(10,20)<<endl;
}