تابع ‎is_long()‎‎ در PHP

<?php
$a = 32;
echo "a is " . is_long($a) . "<br>";

$b = 0;
echo "b is "  . is_long($b) . "<br>";

$c = 32.5;
echo "c is " . is_long($c) . "<br>";

$d = "32";
echo "d is " . is_long($d) . "<br>";

$e = true;
echo "e is " . is_long($e) . "<br>";

$f = "null";
echo "f is " .  is_long($f) . "<br>";
?>