According to the php docs
floatval('122.34343The') == 122.34343
floatval('BLARTLBARTFAST') == 0
Why should it take the input and choose a different response than what floatval would respond with?
If floatval returns null on 'BLARTLBARTFAST' and '122.34343The' then this function should return null. If floatval returns 0 (or whatever) than this function should return the same.
It's inconsistent behavior.
Since you quite clearly have no idea what function we're even talking about or what it's supposed to do, I will just point you to the documentation rather than more explicitly explain on how many levels you are wrong: http://www.php.net/manual/en/function.number-format.php