How can I validate an unsigned number in PHP?

Question

I'm not sure how to handle this one, and I've tried what to me are the most obvious solutions, but so far none have proved entirely satisfactory. I must be overlooking something very simple.

I have a form with an input of type text:

<input type="text" name="album_id">

I want to validate the input so the users only enters unsigned integer...

$required = array(); // required or invalid input

$tmp = trim($_POST['album_id']);

if (!is_int((int)$tmp)) {
   $required['album'] = 'The album id must contain a positive numeric value only.';
}

So far I've use !is_numeric($tmp) but a user can enter 9.2 or '1e4' and it will validate... so that one doesn't work.

I've also tried !is_int((int)$tmp) but for some reason, that one doesn't work (maybe it should but i'm doing it wrong...). I tried ctype_digit with no success. I'm probably overlooking something but not sure what.

How can I validate an unsigned number in php? No floats, negative numbers, etc... only a simple unsigned number (1 to n).

Answer 1

If you want to check if some variable only contains digits (which seems to be what you want, here), you'll probably have to go with ctype_digit().

Not sure what you tried, but something like this should work :

$tmp = trim($_POST['album_id']);
if (ctype_digit($tmp)) {
    // $tmp only contains digits
}