<?php

function bsearch(array $array, int $target): int {
    $min = 0;
    $max = count($array) - 1;
    while ($max >= $min) {
        $mid = floor(($min + $max) / 2);
        if ($target == $array[$mid]) {
            return $mid;
        }
        if ($target > $array[$mid]) {
            $min = $mid + 1;
        } else {
            $max = $mid -1;
        }
    }
    return -1;
}

$array = [1, 2, 3, 4, 5];
for ($i = 0; $i < 7; $i++) {
    echo bsearch($array, $i) . PHP_EOL;
}