// ============================================================================
// file: Sample.cpp
// ============================================================================
// Programmer: Scott Edwards
// Date: 09/15/2014
// Class: CSCI 123 ("Intro to Programming Using C++")
// Time: MW 11:00am
// Instructor: Mr. Edwards
// Project: LoopSum
//
// Description:
//      This program is a contrived example to illustrate the coding style
//      guidelines handout.  The user is prompted for a positive integer, which
//      is used as an upper bound for a loop.  Then the sum of all integers 
//      from one to the upper bound is calculated and displayed to the standard
//      output stream.
//
// ============================================================================

#include    <iostream>
#include    <cstdlib>
using namespace std;

// function prototypes
int     CalcSum(int  limit);
bool    IsValidInt(int  value);


// ==== main ==================================================================
//
// ============================================================================

int     main()
{
    bool        bIsValid;
    int         sum;
    int         upperBound;

    // get the upper bound from the user
    cout << "Please enter a positive integer value: ";
    cin >> upperBound;

    // make sure the value is valid
    bIsValid = IsValidInt(upperBound);
    if (false == bIsValid)
        {
        cout << "Sorry, you must enter a positive value\n";
        exit(EXIT_FAILURE);
        }

    // calculate the sum from one to the upper bound
    sum = CalcSum(upperBound);

    // display the results to stdout
    cout << "The sum is " << sum << endl;
    return 0;

}  // end of "main"



// ==== CalcSum ===============================================================
//
// This function calculates the sum from one to the limit parameter
// (inclusive), then returns the value to the caller.
//
// Input:
//      limit [IN]  -- an integer value containing the upper bound for the
//                     calculation of the sum
//
// Output:
//      The sum of all integers from one to the value of the limit parameter.
//
// ============================================================================

int     CalcSum(int  limit)
{
    int         counter;
    int         total;

    for (counter = 1, total = 0; counter <= limit; ++counter)
        {
        total = total + counter;
        }

    return total;

}  // end of "CalcSum"



// ==== IsValidInt ============================================================
//
// This function tests the input value to make sure that it is positive.  If it
// is, a value of "true" is returned; else, a value of "false" is returned.
//
// Input:
//      value [IN]   -- an integer value to be tested
//
// Output:
//      A value of "true" is returned if the input parameter is positive,
//      otherwise a value of "false" is returned.
//
// ============================================================================

bool    IsValidInt(int  value)
{
    bool        bRetVal;

    // if the input value is less than zero, return "false", else return "true"
    if (value < 0)
        {
        bRetVal = false;
        }
    else
        {
        bRetVal = true;
        }

    return bRetVal;

}  // end of "IsValidInt"