C programs to display array elements in reverse order have been shown here. Both of the iterative and recursive approaches have been covered. The algorithm, pseudocode and time complexity of the programs have also been given.

Example:

Given array A[] = {10, 20, 30, 40}

Elements of A[] in reverse order = {40, 30, 20, 10}

#### Page content(s):

1. Algorithm

2. Pseudocode

3. Time Complexity

4. Program & output

## 1. Algorithm to display array elements in reverse order

1. Take input of an array $A[~]$ and the size $n$

2. Set $i = n - 1$

3. For each $i$ from $n - 1$ to $0$, dislay $A[i]$

## 2. Pseudocode to display array elements in reverse order

Input: An array $A[~]$ and size of array $n$

Output: Array elements in reverse order.

1. Procedure reverse($A[~]$, $n$):

2. Repeat for $i \in [n-1, 0]$:

3. Print $A[i]$

4. End Procedure

## 3. Time complexity to display array elements in reverse order

Time Complexity: O(n)

Here $n$ is the number of elements in the array.

## 4.1. C Program & output to display array elements in reverse order using iterative approach

Code has been copied
/************************************
alphabetacoder.com
C program to print elements of array
in reverse order using iteration
*************************************/

#include <stdio.h>

int main() {
// declare an array
int arr[8] = {10, 20, 30, 40, 50, 60, 70, 80};
// declare variables
int i, length;

// calculate size of array
length = sizeof(arr) / sizeof(arr[0]);

// display the array
printf("Original array: ");
for (i = 0; i < length; i++)
printf("%d ", arr[i]);

// display array elements in reverse order
printf("\nReverse array : ");
for (i = length - 1; i >= 0; i--)
printf("%d ", arr[i]);

return 0;
}


Output

Original array: 10 20 30 40 50 60 70 80

Reverse array : 80 70 60 50 40 30 20 10

## 4.2. C Program to display array elements in reverse order using pointer

Code has been copied
/************************************
alphabetacoder.com
C program to print elements of array
in reverse order using pointer
*************************************/

#include <stdio.h>

int main() {
// declare an array
int arr[8] = {10, 20, 30, 40, 50, 60, 70, 80};
// declare variables
int i, length, * p;

// calculate size of array
length = sizeof(arr) / sizeof(arr[0]);

// display the array
printf("Original array: ");
for (i = 0; i < length; i++)
printf("%d ", arr[i]);

// pointer p points to the last element of array arr
p = & arr[length - 1];

// display array elements in reverse
// order using pointer p
printf("\nReverse array : ");
for (i = length - 1; i >= 0; i--)
printf("%d ", * p--);

return 0;
}


## 4.3. C Program to display array elements in reverse order using recursion

Code has been copied
/***********************************
alphabetacoder.com
C program to print elements of array
in reverse order using recursion
*************************************/

#include <stdio.h>

// display elements of array in reverse
// order function takes an array arr and
// an index i as arguments
void reverse(int arr[], int i) {
// exit condition of recursive call
if (i < 0)
return;
// print current element
printf("%d ", arr[i]);
// call function
reverse(arr, i - 1);
}

int main() {
// declare an array
int arr[8] = {10, 20, 30, 40, 50, 60, 70, 80};
// declare variables
int i, length;

// calculate size of array
length = sizeof(arr) / sizeof(arr[0]);

// display the array
printf("Original array: ");
for (i = 0; i < length; i++)
printf("%d ", arr[i]);

// display array elements in reverse
// order using recursive function reverse()
// pass array arr and last index of array as
// arguments
printf("\nReverse array : ");
reverse(arr, length - 1);

return 0;
}