<?php
 
function isPalindrome($string)
{
    $middlePoint = strlen($string) / 2;
    return (strcmp(substr($string, 0, $middlePoint), strrev(substr($string, -$middlePoint))) == 0);
}

var_dump(isPalindrome("lol"));
var_dump(isPalindrome("hello"));
var_dump(isPalindrome("10021"));
var_dump(isPalindrome("10001"));
var_dump(isPalindrome("2001"));
var_dump(isPalindrome("1001"));