Referencing Array Variables

klycette

I think this is really easy, but I'm not getting it. I know that any form field can be referenced on the page that the information is posted to by putting a $ in front of it (asssuming globals are turned on, which is the case in the host that I have access to).

On one of my forms, I have an array, called categories[] and I'm trying to give users an error if they don't choose at least one item in the list. Unfortunately, if I can't access it via $categories like any other form field because I keep getting an undefined variable message. $categories[] doesn't work either. These problems only exist when nothing is selected, otherwise it works fine.

How do you access the array variable? Thanks in advance.

LordShryku

You could just look for the first part of the array, which in this case is $catgories[0]
Or you can count the array...

if(count($categories) == 0) {
    echo "empty";
}
else {
    echo count($categories)." values in the array";
}

klycette

Thanks for the response, but that's not really the problem that I'm having. My problem is that whenever I use $categories, it gives me an undefined variable error.

It seems that I can reference any other form field using $firstname, $lastname, etc, but I can't reference the categories[] array in the same way. That's what I'm looking for...how do I reference the array correctly so I don't get the error? I've tried $categories[], but that doesn't work either. Thanks.

trexx

i see... i assume that you have an array of checkboxes on your form. now, it's a characteristic of html/http that unchecked checkboxes or radio buttons are NOT being transmitted at all!

So if you don't check at least one checkbox PHP will not know that it has to create an array out of the (not) submitted values.

The trick is to check, if the array is set first. you do that with:

if(isset($myArray) && count($myArray) > 0)
...

klycette

Yeah, that did it. Thanks. I actually tried that before, but I just found an error in my code somewhere else that prevented me from seeing that it would have worked. Again, thanks. By the way, it was actually a multi-select listbox, but the same principle applied.

superwormy

Just a note, regardless of whether or not your host has register_globals turned ON or OFF, you should ALWAYS be using $POST, $GET, $_COOKIE and NEVER just be using $varname to access variables coming through POST data, the URL, or Cookies.