Question

C++

9.10: Reverse Array Write a function that accepts an int array and the array’s size as arguments. The function should create a copy of the array, except that the element values should be reversed in the copy. The function should return a pointer to the new array. Demonstrate the function by using it in a main program that reads an integer N (that is not more than 50) from standard input and then reads N integers from a file named data into an array. The program then passes the array to the your reverse array function, and prints the values of the new reversed array on standard output, one value per line. You may assume that the file data has at least N values. Prompts And Output Labels. There are no prompts for the integer and no labels for the reversed array that is printed out. Input Validation. If the integer read in from standard input exceeds 50 or is less than 0 the program terminates silently.

Answer 1

Code

#include <iostream>
#include <string>
#include<fstream>

using namespace std;

int* reverseArray(int arr[], int N)
{
   int j = N - 1;
   int *newArray = (int*)malloc(N * sizeof(int));
   for (int i = 0; i < N; i++)
       newArray[i] = arr[j--]; // assigning value to new array in reverse order from original array.

   return newArray;
}

int main()
{
   int N = 0, *arr=NULL, *revArr=NULL;
   cout << "Enter the number of elements" << endl;
   cin >> N;

   // Input Validation
   if (N <= 0 || N > 50)
       return 0;

   // Dynamically create an array with N elements
   arr = (int*)malloc(N * sizeof(int));

   // Read the array value from file named "data.txt"
   ifstream file ("data.txt");
   if (file.is_open())
   {
       for (int i = 0; i < N; i++)
       {
           string line;
           getline(file, line); // Reading each number as string

           arr[i] = atoi(line.c_str()); // converting into integer and storing in array
       }
   }
   else
   {
       cout << "could not open the file\n";
       return 0;
   }

   revArr = reverseArray(arr, N);
   cout << endl;
   for (int i = 0; i < N; i++)
       cout << revArr[i] << endl;

   return 0;
}

Test Input

data.txt file

Test Output