The number 0 is not being passed through.

Question

I had a problem with a piece of code i just developed and I have narrowed it down to the number 0 not being accepted.

This is the html

<input type="text" size="1" name="hs" maxlength='3'>

If I enter ZERO into that input box it gives an error saying nothing has been entered.

Once I have passed this through, this is the PHP error handling code

$field = "hs"; 
    if((!$hs) || strlen($hs = trim($hs)) == 0)
    {
        $form->setError($field, "* Home score not entered");

    }

    $field = "as"; 
    if((!$as) || strlen($as = trim($as)) == 0)
    {
        $form->setError($field, "* Away score not entered");

    }

I am getting those errors if I enter the score at a 0. Any ideas why this is happening? Is it something any of you have experienced?

THanks

Answer 1

!0 is true in PHP, so the first if clause is being executed.

Answer 2

PHP interprets both the text string '0' and the number 0 as false. Implicit type conversion is sometimes handy and sometimes annoying. (What you're getting from the form is the string '0').

Try something like

if (strlen($hs = trim($hs)) == 0) {
    $form->setError($field, "* Home score not entered");
} elseif (!is_numeric($hs)) {
    $form->setError($field, "* Score must be a number");
}

Answer 3

As others have said, the value 0 is interpreted as false. (so the expression !0 is true)

Hey -- you're not using register_globals are you?

What you should be doing is isset($_GET['hs']), and fetch the value of the variable using $_GET['hs'] as well.

Using register_globals is a HUGE security liability.

Answer 4

You could try this if condition instead:

$hs = trim($hs);

// !== does a strict, type-sensitive comparison against the string '0'
if (($hs !== '0' && !$hs) || strlen($hs) == 0)
{
    $form->setError($field, "* Home score not entered");
}

Answer 5

if(! isset($hs) || ! is_numeric($hs) || $hs < 0) {
    //error
}

I personally don't know why you would want to do a strlen on it, surely an $hs == "" would suffice?

Answer 6

I would suggest just dropping the !$hs. Your strlen($hs) should be sufficient for what you're trying to test. The only thing I might add is making user $hs isset so you don't get an undefined error.