Implementation of binary search on sorted array of integers in C

binary_search.c

#include <stdio.h>
#include <stdlib.h>


int binary_search(const int *arr, const int arr_len, const int n);

int main(int argc, char *argv[])
{
   if (argc != 2)
   {
      puts("Invalid argument specification.");
      return !EXIT_SUCCESS;
   }

   const int sorted_items[] = { -1000, -21, 2222, 305840, 400000, 5123456, 6000000, 999999999 };
   const int len_items      = sizeof(sorted_items) / sizeof(*sorted_items);
   const int search_number  = atoi(argv[1]);

   // Binary search
   int idx = binary_search(sorted_items, len_items, search_number);

   if (idx >= 0)
   {
      printf("Input number found at index %d in `sorted_items`!\n", idx);
      return EXIT_SUCCESS;
   }
   else
   {
      puts("Input number not found in `sorted_items`!");
      return !EXIT_SUCCESS;
   }
}


/* Iterative implementation */
int binary_search(const int *arr, const int arr_len, const int n)
{
   int start_idx = 0;
   int end_idx   = arr_len - 1;
   int mid_idx;
   
   // "Edge" cases
   if ((arr_len == 0) || (n < arr[0]) || (n > arr[arr_len - 1]))
   {
      return -1;
   }

   do
   {
      mid_idx = start_idx + ((end_idx - start_idx) / 2);
      if (arr[mid_idx] > n)
      {
         end_idx = mid_idx;
      }
      else if (arr[mid_idx] < n)
      {
         start_idx = mid_idx;
      }
      else
      {
         return mid_idx;
      }
   } while ((end_idx - start_idx) > 1);

   return -1;
}

binary_search.py

#!/usr/bin/env python3

import random
import sys


def main(n: int) -> None:
    """
    Program entrypoint to search pre-defined `sorted_arr` for `n` from user input
    """
    rand_arr = [random.randint(-20, 20) for _ in range(10)]
    sorted_arr = sorted(rand_arr)

    print(sorted_arr)

    if len(sorted_arr) == 0:
        print(f"The number {n} was NOT found because `sorted_arr` is empty.")

    else:
        found_idx = binary_search(sorted_arr, n)
        if found_idx > 0:
            print(f"The number {n} was found at index {found_idx}!")
        else:
            print(f"The number {n} was NOT found.")

    return


def binary_search(
    sorted_arr: list, n: int, start_idx: int = 0, end_idx: int = None
) -> int:
    """
    Recursive implementation of binary search for `n` over `sorted_arr`
    """

    end_idx = len(sorted_arr) - 1 if end_idx is None else end_idx
    mid_idx = start_idx + ((end_idx - start_idx) // 2)

    # Base case
    if len(sorted_arr[start_idx:end_idx]) == 1:
        return start_idx if sorted_arr[0] == n else -1

    # Recursive case
    if sorted_arr[mid_idx] == n:
        return mid_idx
    elif sorted_arr[mid_idx] > n:
        return binary_search(sorted_arr, n, start_idx, mid_idx)
    else:
        return binary_search(sorted_arr, n, mid_idx, end_idx)


if __name__ == "__main__":
    n = int(sys.argv[1])
    main(n)

Added recursive implementation of binary search in Python as supplement to the iterative implementation in C.