<?php

$arr = [7,10,15, 23, 25,40,55,78,98];
$search_element = 1;
$end = count($arr) -1;//6
$start = 0;
//If mid > element, traverse left OR mid < element, traverse right
$found = 0;
//echo count($arr)." ".$start;
while($end >= $start){

    $mid = (int)($start + ($end - $start)/2);

    if($arr[$mid] == $search_element){
        $found = 1;break;
        
    }elseif($arr[$mid] > $search_element){
        $end = $mid -1; 
        
    }elseif($arr[$mid] < $search_element){
        $start = $mid +1; 
    }
    
}

echo($found);