Program to reverse an array or string

Program to reverse an array or string

Given an array (or string), the task is to reverse the array/string.

Method 1(Iterative way):

// Iterative C program to reverse an array

#include<stdio.h>

/* Function to reverse arr[] from start to end*/

void rvereseArray(int arr[], int start, int end)

{

    int temp;

    while (start < end)

    {

        temp = arr[start];  

        arr[start] = arr[end];

        arr[end] = temp;

        start++;

        end--;

    }  

}    

/* Utility that prints out an array on a line */

void printArray(int arr[], int size)

{

  int i;

  for (i=0; i < size; i++)

    printf("%d ", arr[i]);

  printf("\n");

}

/* Driver function to test above functions */

int main()

{

    int arr[] = {1, 2, 3, 4, 5, 6};

    printArray(arr, 6);

    rvereseArray(arr, 0, 5);

    printf("Reversed array is \n");

    printArray(arr, 6);   

    return 0;

}

Output :

1 2 3 4 5 6

Reversed array is

6 5 4 3 2 1

Method 2(recursive way):

// Recursive C program to reverse an array

#include <stdio.h>

/* Function to reverse arr[] from start to end*/

void rvereseArray(int arr[], int start, int end)

{

   int temp;

   if (start >= end)

     return;

   temp = arr[start];  

   arr[start] = arr[end];

   arr[end] = temp;

   rvereseArray(arr, start+1, end-1);  

}    

/* Utility that prints out an array on a line */

void printArray(int arr[], int size)

{

  int i;

  for (i=0; i < size; i++)

    printf("%d ", arr[i]);

  printf("\n");

}  

/* Driver function to test above functions */

int main()

{

    int arr[] = {1, 2, 3, 4, 5, 6};

    printArray(arr, 6);

    rvereseArray(arr, 0, 5);

    printf("Reversed array is \n");

    printArray(arr, 6);   

    return 0;

}

Output :

1 2 3 4 5 6

Reversed array is

6 5 4 3 2 1

Examples :

Input  : arr[] = {1, 2, 3}

Output : arr[] = {3, 2, 1}

Input :  arr[] = {4, 5, 1, 2}

Output : arr[] = {2, 1, 5, 4}