Reverse of an Array in C++

March 29, 2023

Reverse of an array in C++ Programming Language

On this page, we will look into a coding question where we will learn how to reverse the array in C++ Programming Language. There might be different approaches to solve this question, one you will find here. If your approach is a bit different post it in the comment section.

Reverse of an Array In C++ Programming

In C++, reversing an array means rearranging the elements of the array in the opposite order. That is, the first element of the array becomes the last element, the second element becomes the second to last element, and so on.

Note The time complexity for reversing an array is O(n/2) or simply O(n), where n is the size of the array.

Introduction to 2-D Arrays

Array Rotation

Majority Element in Array

Find pairs in array with given sum

Sort the array in Waveform

Algorithm

Declare an array and its size.
Initialize two pointers start and end, pointing to the first and last element of the array, respectively.
Swap the elements at the start and end pointers using a temporary variable.
Increment the start pointer and decrement the end pointer.
Repeat steps 3-4 until the start pointer becomes greater than or equal to the end pointer.
The array is now reversed.

C++ Code Reverse of an Array

Run

#include <iostream>
using namespace std;

int main ()
{
  int arr[] = { 1, 2, 3, 4, 5 };
  int n = sizeof (arr) / sizeof (arr[0]);

  int start = 0;
  int end = n - 1;

  // swap elements at start and end until start >= end
  while (start < end)
    {
      int temp = arr[start];
      arr[start] = arr[end];
      arr[end] = temp;

      start++;
      end--;
    }

  // print the reversed array
  for (int i = 0; i < n; i++)
    {
      cout << arr[i] << " ";
    }

  return 0;
}

Output

5 4 3 2 1

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