how to do binary search in c 2b 2b using stl

1// BY shivam kumar KIIT
2#include<bits/stdc++.h>
3usind namespace std;
4int main()
5{
6	int arr[]={10,2,34,2,5,4,1};
7  	sort(arr,arr+7);//sort array in ascending order before using binary search
8  	binary_search(arr,arr+7,10);//return 1 as element is found
9  	binary_search(arr,arr+7,3);//return 0 as element is not found
10  	return 0;
11}

1#include<iostream>
2using namespace std;
3int binarySearch(int arr[], int p, int r, int num) {
4   if (p <= r) {
5      int mid = (p + r)/2;
6      if (arr[mid] == num)
7      return mid ;
8      if (arr[mid] > num)
9      return binarySearch(arr, p, mid-1, num);
10      if (arr[mid] > num)
11      return binarySearch(arr, mid+1, r, num);
12   }
13   return -1;
14}
15int main(void) {
16   int arr[] = {1, 3, 7, 15, 18, 20, 25, 33, 36, 40};
17   int n = sizeof(arr)/ sizeof(arr[0]);
18   int num = 33;
19   int index = binarySearch (arr, 0, n-1, num);
20   if(index == -1)
21   cout<< num <<" is not present in the array";
22   else
23   cout<< num <<" is present at index "<< index <<" in the array";
24   return 0;
25}