Programming Challenge 9.10 - Reverse Array

/* Reverse Array - This program contains a function that accepts an int
   array and the array's size as arguments. The function creates a copy
   of the array, except that the element values are reversed in the copy.
   The function returns a pointer to the new array. */

#include "Utility.h"

/* Function prototypes */
void getNumbers(int *, int);
int *reverseNumbers(const int *, const int);
void displayNumbers(const int *, const int);
void displayReverse(const int *, const int);
void freeMem(int *, int *);

int main()
{
   int *numbers = nullptr;
   int *revNumbers = nullptr;

   int numels = 0;

   /* Get the initial number of elements the array should contain */
   cout << "\tREVERSE NUMBERS\n\n"
        << "\tHow many numbers should your set contain? ";
   cin >> numels;

   /* Allocates a new array to hold the numbers */
   numbers = new int[numels];

   /* Creates a set of random numbers to fill the numbers array */
   getNumbers(numbers, numels);

   /* Displays the numbers in their original order */
   displayNumbers(numbers, numels);

   /* Creates a copy of numbers and fills the copy with the numbers
      in reverse order */
   revNumbers = reverseNumbers(numbers, numels);

   /* Displays the numbers in reverse order */
   displayReverse(revNumbers, numels);

   /* Frees the memory */
   freeMem(numbers, revNumbers);

   pauseSystem();
   return 0;
}

/* **********************************************************
   Definition: getNumbers

   This function accepts numbers and numels as arguments. It
   fills numbers with (pseudo)random numbers in the range of
   1 through 200.
   ********************************************************** */

void getNumbers(int *numbers, int numels)
{
   const int MIN_NUM = 1,
             MAX_NUM = 200;

   srand((unsigned int) time(NULL));

   for (int index = 0; index < numels; index++)
   {
      *(numbers + index) = (rand() % (MAX_NUM - MIN_NUM + 1) + MIN_NUM);
   }
}

/* **********************************************************
   Definition: displayNumbers

   This function accepts numbers and numels as arguments. It
   displays the numbers in their original order.
   ********************************************************** */

void displayNumbers(const int *numbers, const int numels)
{
   cout << "\n\tThese are your numbers in their original order:\n\n";

   for (int index = 0; index < numels; index++)
   {
      cout << "\t" << *(numbers + index) << " \n";
   }
}

/* **********************************************************
   Definition: reverseNumbers

   This function accepts numbers and numels as arguments. It
   creates a copy of the array, and reverses the numbers. A
   pointer to the copy containing the numbers in reverse
   order is returned.
   ********************************************************** */

int *reverseNumbers(const int *numbers, const int numels)
{
   int *revNumbers = nullptr;

   int firstElem = 0,
       lastElem = numels;

   /* Allocates a new array to hold the copy  of numbers in
      reverse order */
   revNumbers = new int[numels]();

   while (lastElem > 0)
   {
      --lastElem;
      *(revNumbers + firstElem) = *(numbers + lastElem);
      ++firstElem;     
   }

   /* Returns a pointer to the new array */
   return revNumbers;
}

/* **********************************************************
   Definition: displayReverse

   This function accepts revNumbers and numels as arguments. It
   displays the numbers in reverse order.
   ********************************************************** */

void displayReverse(const int *revNumbers, const int numels)
{
   cout << "\n\tThese are your numbers in reverse order:\n\n";

   for (int index = 0; index < numels; index++)
   {
      cout << "\t" << *(revNumbers + index) << " \n";
   }
}

/* **********************************************************
   Definition: freeMem

   This function accepts numbers and numels as arguments. It
   frees the memory before the program exits.
   ********************************************************** */

void freeMem(int *numbers, int *revNumbers)
{
   delete[] numbers;
   delete[] revNumbers;

   numbers = nullptr;
   revNumbers = nullptr;
}

Example Output: