<?php 
  
function binarySearch(array $arr, int $target): int 
{ 
    $low = 0; 
    $high = count($arr) - 1; 
      
    while ($low <= $high) {          
        // compute middle index 
        $mid = floor(($low + $high) / 2);  
  
        if ($arr[$mid] > $target) { 
            // search the left side of the array 
            $high = $mid -1; 
        } else if ($arr[$mid] < $target) { 
            // search the right side of the array 
            $low = $mid + 1; 
        } else {
            // element found at mid 
            return $mid; 
        }
    } 
      
    // If we reach here element x doesnt exist 
    return -1; 
} 
  
// Driver code 
$arr = [1, 2, 3, 4, 5]; 
$target = 3;
$result = binarySearch($arr, $target);

if($result !== -1) { 
    echo "Target '$target' exists at position $result"; 
} else {
    echo "Target '$target' does not exist";
}

# Returns index of target in arr if present, else -1
def binary_search(arr, target):
	low = 0
	high = len(arr) - 1

	while low <= high:
		# Check base case
		mid = (high + low) // 2

		# If element is smaller than mid, then it can only
		# be present in left subarray
		if arr[mid] > target:
			high = mid - 1
		# Else the element can only be present in right subarray
		elif arr[mid] < target:
			low = mid + 1
		# If element is present at the middle itself
		else:
			return mid

	# Element is not present in the array
	return -1

# Test array
arr = [ 2, 3, 4, 10, 40 ]
target = 10

result = binary_search(arr, target)

if result != -1:
	print("Element is present at index", str(result))
else:
	print("Element is not present in array")

package main

import "fmt"

// return target index if it exists in arr
func search(arr []int, target int) int {
    low := 0
    high := len(arr) - 1

    for low <= high {
        mid := (low + high) / 2

        if arr[mid] < target {
            low = mid + 1
        } else if arr[mid] > target {
            high = mid - 1
        } else {
            return mid
        }
    }

    return -1
}

func main() {
    target := 7
    items := []int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}
    fmt.Printf("Element '%d' index is %d", target, search(items, target))
}

// $ output
// 6