BinarySearch

// C++ program to implement recursive Binary Search
#include <iostream>

using namespace std;


// A recursive binary search function. It returns
// location of x in given array arr[l..r] is present,
// otherwise -1

int binarySearch(int arr[], int l, int r, int x)
{

    if (r >= l) {

        int mid = l + (r - l) / 2;



        // If the element is present at the middle

        // itself

        if (arr[mid] == x)

            return mid;



        // If element is smaller than mid, then

        // it can only be present in left subarray

        if (arr[mid] > x)

            return binarySearch(arr, l, mid - 1, x);



        // Else the element can only be present

        // in right subarray

        return binarySearch(arr, mid + 1, r, x);

    }



    // We reach here when element is not

    // present in array

    return -1;
}



int main(void)
{
  char choice;
  char string;

    int arr[] = { 5, 10, 15, 20 ,25, 50, 65, 70, 90, 100 };

    int x;
         cout << "input your choice" << endl << endl;
         cin >> x;

    int n = sizeof(arr) / sizeof(arr[0]);

    int result = binarySearch(arr, 0, n - 1, x);

    (result == -1) ? cout << "Element is not present in array"

                   : cout << "Element is present at index " << result;

    return 0;
}