PHP pre-defined error displaying

[Dormilich]

what was the message again?

[Matt Morgan]

We are very sorry, but there were error(s) found with the form you submitted. These errors appear below.

The RAID you entered do not appear to be valid.
The Accessories you entered do not appear to be valid.
The Guarantee you entered do not appear to be valid.

Please go back and fix these errors.

[Dormilich]

I thought it were a PHP error message. nevertheless, the problem is your validation strategy. the last time we were at "how would you check that a variable is an integer?" any ideas?

[Matt Morgan]

They are predefined error messages on the PHP which, when an error occurs, display on the screen. I honestly have no idea.

[Dormilich]

you have no idea what the difference between 1 and "q" is?

[Matt Morgan]

Well thats clearly a number and a letter...

[Dormilich]

and how do you know what a number and a letter is?

[Matt Morgan]

Well I went to school...

[Dormilich]

does PHP can go to school? obviously not. hence you have to tell PHP in its (PHP’s) vocabulary (read: PHP functions & language constructs) what you learned is the difference between a number and a letter. though chances are that PHP already has a basic vocabulary for letters and numbers.

[Matt Morgan]

So what are you suggesting I do?
I know I have to change this:

    if(strlen($RAID) < raid (4) Y (1), N (1)) {
        $error_message .= 'The RAID you entered do not appear to be valid.<br />';   
      }

for the respective parts which are not working, I just don't know what to.

[Matt Morgan]

The $error_message is working, I know that much, so I'm assuming it's just the top 'if' statement which is causing the issue.