/*
 **************************************************************************
 * Program name : 006_Area_of_Circle (Version 1.00)                       *
 * Author       : Duck Wong                                               *
 * Language     : C / C++                                                 *
 * Compiler     : Boodshed Dec-C++ compiler Ver 3.95                      *
 * Computer     : PII350                                                  *
 * O/S          : Windows 98                                              *
 **************************************************************************
 * Version 1.00 : 2000/06/04 - first version                              *
 **************************************************************************
 * Description  : (a) intut the radius of a circle                        *
 *                (b) calculate the area, diameter and circumference      *
 *                (c) output results                                      *
 **************************************************************************
*/
#include <iostream>
#include <stdlib.h>

int main()
{
 // Part 1 : declaration
 const float pi = 3.14159;                                           // Note (1)
 float radius, area, diameter, circumference;
 char  again = 'Y';                                                  // Note (2)

 while (again=='Y'||again=='y')                                // Note (3) & (4)
   {
    // Part 2 : input
    cout << "\nPlease input the radius of the circle : ";
    cin  >> radius;

    // Part 3 : calculation
    diameter = 2*radius;
    area = radius*radius*pi;
    circumference = diameter*pi;

    // Part 4 : output
    cout << "\nThe diameter is : " << diameter
         << "\nThe area is     : " << area
         << "\nThe circumference is : " << circumference << "\n" << endl;

    // Part 5 : run this program again
    cout << "\n\a  Try again (Y/N) : ";
    cin  >> again;
   };  //End of while loop

 system("PAUSE");
 return 0;
}

/* Notes
   (1) const float pi=3.14159;  =>  CONST pi=3.14159; (in Pascal)
       float pi = 3.14159 means set the value of 3.14159 to identifier pi

   (2) char again = 'Y' means set the value of 'Y' to identifier 'again'

   (3) (again=='Y'||again=='y')
       = ((again='Y')or(again='y')) in Pascal

   (4) Unlike Pascal, the while loop statement in C++ does not use 'DO'.
*/