/**************************************************************************/
/* Author: Chang												          */
/* Aim for: CS135 class				   									  */
/* Problem: Write a program that will receive a small pizza size and      */
/*         price and calculate the price per square inch for the small    */
/*         size and a large size (4'' larger).  Using function.	          */
/**************************************************************************/
//preprocessor directives
#include <iostream>
#include <cmath>          // needed for using pow() function
using namespace std;

// function prototype
double Calculate_Price_Per_Square(double, double); 
void prettyPrintDouble(double x);
void prettyPrintString(string s);

int main ()
{
    double small_pizza_diameter, large_pizza_diameter, pizza_price, large_pizza_price;
    double small_unit_price, large_unit_price;

    // Get Inputs
    cout << "Enter the diameter of a round pizza (inches): ";
    cin >> small_pizza_diameter;
    cout << "Enter the price of the pizza ($):  ";
    cin >> pizza_price;
    cout << "Enter the price of 4'' larger pizza ($):  ";
    cin >> large_pizza_price;
    
    // initialize large_pizza_diameter
    large_pizza_diameter = small_pizza_diameter + 4;
    
    // Function call
    // Calculate the prices per square inch 
    small_unit_price = Calculate_Price_Per_Square(small_pizza_diameter, pizza_price);
    large_unit_price = Calculate_Price_Per_Square(large_pizza_diameter, large_pizza_price);
    
    // Print outputs
    prettyPrintString( "Diameter");
    prettyPrintString( "Price");
    prettyPrintString( "Unit Price");
    cout << endl;
    prettyPrintDouble(small_pizza_diameter);
    prettyPrintDouble(pizza_price);
    prettyPrintDouble(small_unit_price);
    cout << endl;
    prettyPrintDouble(large_pizza_diameter);
    prettyPrintDouble(large_pizza_price);
    prettyPrintDouble(large_unit_price);
    cout << endl;   
    
    system ("PAUSE");
    return 0;
}

// function body
double Calculate_Price_Per_Square(double d, double p)
{
    const double PI = 3.14;
    double size;
    double PricePerSquare;
    // size = PI * (d * d) / 4.0;
    size = PI * ( pow(d, 2.0) ) / 4.0;
    PricePerSquare = p / size;
    return PricePerSquare; 
}

// function body
void prettyPrintDouble(double x){
  char tmp[21];
  sprintf(tmp, "%15.2lf", x);
  cout << tmp;
  return;
}

// function body
void prettyPrintString(string s){
  char tmp[21];
  sprintf(tmp, "%15s", s.c_str());
  cout << tmp;
  return;
}