Reverse the array/string.

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

Examples : 
 

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

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

1) Initialize start and end indexes as start = 0, end = n-1 
2) In a loop, swap arr[start] with arr[end] and change start and end as follows : 
start = start +1, end = end – 1

Another example to reverse a string:

Below is the implementation of the above approach : 

// Iterative C# program to reverse an
// array
using System;

class GFG {

	/* Function to reverse arr[] from
	start to end*/
	static 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 */
	static void printArray(int []arr,
							int size)
	{
		for (int i = 0; i < size; i++)
			Console.Write(arr[i] + " ");
		
		Console.WriteLine();
	}
	
	// Driver function
	public static void Main()
	{
		int []arr = {26,7,56,89,34,45,89};
		printArray(arr, 6);
		rvereseArray(arr, 0, 5);
		Console.Write("Reversed array is \n");
		printArray(arr, 6);
	}
}

// This code is contributed by Anil Dwivedi

Output :

26 7 56 89 34 45 
Reversed array is 
45 34 89 56 7 26