/* Filename:  rounding.cpp

   Author:  Br. David Carlson
            Br. Isidore Minerd

   Date:  January 11, 2005

   Modified: July 16, 2009

   This program tests various ways to implement a rounding function.
   The program simply outputs a list of numbers along with their
   rounded values as computed by each rounding function.

   Tested with:
      Microsoft Visual C++ 6.0
      Microsoft Visual C++ .NET
      Microsoft Visual Studio 2008
      g++ under Linux
*/

#include <iostream>
#include <cmath>     // Needed for using the pow function.
#include <iomanip>   // Needed for using setw.
using namespace std;

// Function prototypes:
float Round1(float Value);
float Round2(float Value);
float Round3(float Value, int NumPlaces);
float Round4(float Value, int NumPlaces);


int main(void)
   {
   float Value;
   
   cout.setf(ios::fixed);
   cout.setf(ios::showpoint);
   cout.precision(5);
      
   cout << setw(10) << "Value" << setw(10) << "Round1" << setw(10) <<
      "Round2"  << setw(10) << "Round3" << setw(10) << "Round4" << endl;
   
   Value = 7.86;
   cout << setw(10) << Value << setw(10) << Round1(Value) << setw(10) <<
      Round2(Value) << setw(10) << Round3(Value, 2) << setw(10)
      << Round4(Value, 2) << endl;
      
   Value = 2.936;
   cout << setw(10) << Value << setw(10) << Round1(Value) << setw(10) <<
      Round2(Value) << setw(10) << Round3(Value, 2) << setw(10)
      << Round4(Value, 2) << endl;      
   
   Value = 6.164;
   cout << setw(10) << Value << setw(10) << Round1(Value) << setw(10) <<
      Round2(Value) << setw(10) << Round3(Value, 2) << setw(10)
      << Round4(Value, 2) << endl;   
   
   Value = 3.875;
   cout << setw(10) << Value << setw(10) << Round1(Value) << setw(10) <<
      Round2(Value) << setw(10) << Round3(Value, 2) << setw(10)
      << Round4(Value, 2) << endl;  
         
   return 0;
   }
   

/* Given:  Value  a floating point number
   Task:   To round Value to 2 decimal places.
   Return: The rounded number in the function name.
*/   
float Round1(float Value)
   {
   float Product, Answer, Fraction;
   int Whole;
   
   Product = 100 * Value;
   Whole = static_cast<int> (Product);
   Fraction = Product - Whole;
   if (2 * Fraction >= 1)
      return (Whole + 1.0) / 100.0;
   else
      return Whole / 100.0;
   }


/* Given:  Value  a floating point number
   Task:   To round Value to 2 decimal places.
   Return: The rounded number in the function name.
*/   
float Round2(float Value)
   {
   int Temp;
   
   Temp = Value * 100.0 + 0.5;
   return Temp / 100.0;
   }


/* Given:   Value      a floating point number
            NumPlaces  a positive integer giving the number of
                       decimal places to which to round the answer.
   Assumes: That NumPlaces is positive.  No check is made to see
            that it really is.
   Task:    To round Value to NumPlaces decimal places.
   Return:  The rounded number in the function name.
*/   
float Round3(float Value, int NumPlaces)
   {
   float Factor;
   int Temp;
   
   Factor = pow(10.0, NumPlaces);
   Temp = Value * Factor + 0.5;
   return Temp / Factor;
   }


/* Given:   Value      a floating point number
            NumPlaces  a positive integer giving the number of
                       decimal places to which to round the answer.
   Task:    To round Value to NumPlaces decimal places.  If NumPlaces
            is not postive, Value is returned unchanged as the answer.
   Return:  The rounded number in the function name.
*/   
float Round4(float Value, int NumPlaces)
   {
   int k, Temp;
   float Factor;
   
   Factor = 1;
   for (k = 0; k < NumPlaces; k++)
      Factor = Factor * 10;
      
   Temp = Value * Factor + 0.5;
   return Temp / Factor;
   }