Are you sure that $month always has two digits? You are using string comparision for comparing $month to a number, and I find that counterintuitive.

Also, something with your calculations seems weird. Traditionally, month numbers are zero based in Perl, and most functions treat them as such. December will always have 31 days, but you limit it to 30 days, and similarly October. Or your January check makes not much sense, since January can well have more than 29 days, in most cases it even has 31 days.

perl -MHTTP::Daemon -MHTTP::Response -MLWP::Simple -e ' ;    # The  
$d = new HTTP::Daemon and fork and getprint $d->url and exit;#spider
($c = $d->accept())->get_request(); $c->send_response( new   #in the
HTTP::Response(200,$_,$_,qq(Just another Perl hacker\n))); ' #  web
[download]

Am I sure the month will always be two digits? Yes, I'm 100% positive and from the snippet below, it'll also relieve your wonders on why I'm comparing to a number.

With all that beside us now, can someone help me setup the max day checker?

print <<"ALL";

Day: <SELECT NAME="day" SIZE="1">
<OPTION SELECTED> $editday
<OPTION> 01
<OPTION> 02
<OPTION> 03
<OPTION> 04
<OPTION> 05
<OPTION> 06
<OPTION> 07
<OPTION> 08
<OPTION> 09
<OPTION> 10
<OPTION> 11
<OPTION> 12
<OPTION> 13
<OPTION> 14
<OPTION> 15
<OPTION> 16
<OPTION> 17
<OPTION> 18
<OPTION> 19
<OPTION> 20
<OPTION> 21
<OPTION> 22
<OPTION> 23
<OPTION> 24
<OPTION> 25
<OPTION> 26
<OPTION> 27
<OPTION> 28
<OPTION> 29
<OPTION> 30
<OPTION> 31
</SELECT>

Month: <SELECT NAME="month" SIZE="1">
<OPTION SELECTED> $editmonth 
<OPTION> 01
<OPTION> 02
<OPTION> 03
<OPTION> 04
<OPTION> 05
<OPTION> 06
<OPTION> 07
<OPTION> 08
<OPTION> 09
<OPTION> 10
<OPTION> 11
<OPTION> 12
</select>

Year: <SELECT NAME="year" SIZE="1">
<OPTION SELECTED> $edityear
<OPTION>04
<OPTION> 05
<OPTION> 06
</select>
</td></tr>

<tr><td>Course:</td><td>
<SELECT NAME="course" SIZE="1">
<OPTION SELECTED> $course
<OPTION>GDP Mod 1
<OPTION>GDP Mod 2
<OPTION>GDP Mod 3
<OPTION>GDP Mod 4
<OPTION>
<OPTION>HYG Mod 1
<OPTION>HYG Mod 2
<OPTION>HYG Mod 3
<OPTION>
<OPTION>Carers Sp. Needs
<OPTION>VDP
<OPTION>CDP Sp Needs
<OPTION>
<OPTION>TBC
<OPTION>Lecture Day
<OPTION>Other
</SELECT>
[download]

I would do the comparision numerically, because you are, in fact, comparing numbers.

Are you really really sure, that your $month does match /^\d{2}$/ ? Because your OPTION fields seem to contain a space before the number, and I am not really sure whether browsers will strip that space.

For me, your original code works without and problem and I am able without further problem to trigger any of the three conditions.

So I can only recommend really closely checking your input (for example by using the mentioned CGI::Untaint::date, and/or Time::Local). And also revisit your date/time math, as the month you associate with the number 1 will always have 31 days, and not 29 days, even though you cut it off there.

Personally, to make sure an entered date exists, I would use Time::Local, which throws an error for invalid day/month/year combinations.

perl -MHTTP::Daemon -MHTTP::Response -MLWP::Simple -e ' ;    # The  
$d = new HTTP::Daemon and fork and getprint $d->url and exit;#spider
($c = $d->accept())->get_request(); $c->send_response( new   #in the
HTTP::Response(200,$_,$_,qq(Just another Perl hacker\n))); ' #  web
[download]

use Date::Calc qw(
    Days_In_Month
);

if ($days > Days_In_Month($year, $month))
{
    # Bitch and moan
}
[download]

You will need to supply the year, because February changes how many days it has, depending on the year. (It's fickle like that.)

I totally agree with dragonchild about using Date::Calc for date checking and calculation. It greatly simplifies things, and eliminates some subtle and sometimes obscure errors (like checking leap years as above).

(geez, repeat of
Re: Re: Re: Re: Re: Calculating between times? :-)