// File name: circfunc.cpp
// Author: Xiannong Meng
// Course: CS2330
// Date: January 15, 1997
// Modified: January 23, 1997
// Assignment: classroom demonstration
// Problem statement: This program calcualtes radius and circumference
//   of a circle for a given area value, using math. functions.

#include <iostream.h>
#include <math.h>

// constants
const float PI = 3.14159;

// function declaration
void ReadInput(float &);
float Circumference(float);
void DisplayResult( float,float,float);


void main(void)
{
   // variables
   float area;       // input: area of circle
   float radius;     // output: radius of circle
   float circum;     // output: circumference of circle

   // read input
   ReadInput(area);

   // calcualte circle radius, using math function 'sqrt'
   radius = sqrt( area / PI );
   
   // calcualte circle circumference
   circum = Circumference(radius);

   // display the result
   DisplayResult(area, radius, circum);
}

void ReadInput( float & a )
{
   cout << "Enter the area of the circle : ";
   cin >> a;
}

float Circumference( float r )
{
   return (2 * PI * r);
}

void DisplayResult( float a, float r, float c )
{
   cout << "For a given area of " << a << endl;
   cout << "The radius of the circle is " << r << endl;
   cout << "The circumference of the circle is " << c << endl;
}