Building a PHP Calender

Introduction

Today we are going to build a functional calender using PHP.
About a year ago I was given the task of implementing an
events calender on a website. The customer was not a fan of
javascript or ajax, and insisted on a PHP-only
implementation. That made things rather interesting. Gone
were all my dreams of a quick implementation with a jQuery
datepicker. Gone were any thoughts of simplicity whatsoever,
or so I thought. Then it struck me. What was a calender but
just a looping number system? The more I thought about it
the more simple it became. At the end of the day, with a
little research into PHP’s date functions I had come up with
something that actually worked. The working example can be
downloaded here.

We begin by setting a few environmental variables. Obviously
we need to know the URL to our script, and since we are
dealing with a calender we also need to know things about
the date we are at. What we will be doing here is checking
if a variable is set in the URL, telling us what year, month
and day we are looking for, otherwise we will just default
to this year, this month and today.


// set the script location

$self = $_SERVER['PHP_SELF'];

// check if a month variable has been set in the url, else use PHP's date() function to set the current month.

if(isset($_GET['month'])):

    $month = $_GET['month'];

elseif(isset($_GET['viewmonth'])):

    $month = $_GET['viewmonth'];

else: $month = date('m');

endif;


Now we check if a year variable is set in the URL, else use
PHP’s date() function to set the current year
if the current year is not set in the URL.


if(isset($_GET['year'])):

    $year = $_GET['year'];

elseif(isset($_GET['viewyear'])):

    $year = $_GET['viewyear'];

else: $year = date('Y');

endif;