- var_dump: documentation ( source)
- json_encode: documentation ( source)
<?php
$a = '1.23456789012345678';
$b = 111111111111111111.9;
var_dump('Length : ' . strlen($a), (float) $a, $a == (float) $a, $b, 'Missing 8 ' . json_encode(array($a), JSON_NUMERIC_CHECK));