using System;

​

public class BinarySearchExample

{

    public static void Main()

    {

        // The array to be searched (make sure it's sorted for binary search)

        int[] array = { 1, 4, 7, 8, 9, 10, 16, 18, 20, 25 };

​

        Console.Write("Enter the number to search: ");

        int target = int.Parse(Console.ReadLine());

​

        // Perform binary search

        int index = BinarySearch(array, target);

​

        // Display the result

        if (index != -1)

            Console.WriteLine("found at index");

        else

            Console.WriteLine("not found in the array");

    }

​

    // Function to perform binary search

    public static int BinarySearch(int[] array, int target)

    {

        int left = 0;

        int right = array.Length - 1;

​

        while (left <= right)

        {

            int mid = left + (right - left) / 2;

​

            if (array[mid] == target)

                return mid; // Return the index if the target is found

​

            if (array[mid] < target)

                left = mid + 1; // Search in the right half

            else

                right = mid - 1; // Search in the left half

        }

​

        return -1; // Return -1 if the target is not found in the array

    }

}