Code blocks

javascript
function binary_search_iterative(a, value) {
  var mid, lo = 0,
      hi = a.length - 1;
 
  while (lo <= hi) {
    mid = Math.floor((lo + hi) / 2);
 
    if (a[mid] > value) {
      hi = mid - 1;
    } else if (a[mid] < value) {
      lo = mid + 1;
    } else {
      return mid;
    }
  }
  return null;
}

javascript
function binary_search_iterative(a, value) {
  var mid, lo = 0,
      hi = a.length - 1;
 
  while (lo <= hi) {
    mid = Math.floor((lo + hi) / 2);
 
    if (a[mid] > value) {
      hi = mid - 1;
    } else if (a[mid] < value) {
      lo = mid + 1;
    } else {
      return mid;
    }
  }
  return null;
}

rust
//edit to return desired value (the code has bool because usually you need to know whether the element exists or not)
 
fn binary_search<T:PartialOrd>(v: &[T], searchvalue: T) -> bool {
    let mut lower = 0 as usize;
    let mut upper = v.len() - 1;
 
    while upper >= lower {
        let mid = (upper + lower) / 2;
        if v[mid] == searchvalue {
            return true;
        } else if searchvalue < v[mid] {
            upper = mid - 1;
        } else {
            lower = mid + 1;
        }
    }
 
    return false;
}

haskell
import Data.Array (Array, Ix, (!), listArray, bounds)
 
-- BINARY SEARCH USING A HELPER FUNCTION WITH A SIMPLER TYPE SIGNATURE
findIndexBinary
  :: Ord a
  => (a -> Ordering) -> Array Int a -> Either String Int
findIndexBinary p axs =
  let go (lo, hi)
        | hi < lo = Left "not found"
        | otherwise =
          let mid = (lo + hi) `div` 2
          in case p (axs ! mid) of
               LT -> go (lo, pred mid)
               GT -> go (succ mid, hi)
               EQ -> Right mid
  in go (bounds axs)

java
public class BinarySearchRecursive {
 
    public static int binarySearch(int[] haystack, int needle, int lo, int hi) {
        if (hi < lo) {
            return -1;
        }
        int guess = (hi + lo) / 2;
        if (haystack[guess] > needle) {
            return binarySearch(haystack, needle, lo, guess - 1);
        } else if (haystack[guess] < needle) {
            return binarySearch(haystack, needle, guess + 1, hi);
        }
        return guess;
    }
 
    public static void main(String[] args) {
        int[] haystack = {1, 5, 6, 7, 8, 11};
        int needle = 5;
 
        int index = binarySearch(haystack, needle, 0, haystack.length);
 
        if (index == -1) {
            System.out.println(needle + " is not in the array");
        } else {
            System.out.println(needle + " is at index " + index);
        }
    }
}