Building The Foundation - PHP

The calendar we're going to build should have both a "month view" and a "day view" - selecting a specific day from the month view should display scheduled appointments for that day. Options should be available to add new appointments to the list, or edit and delete existing appointments.

This is a good time for you to download the source code, so that you can refer to it throughout this tutorial (you will need a Web server capable of running PHP and a mySQL database in order to run the application).

calendar.zip

We'll begin with the month view, a file I'm going to call "month.view.php". The first thing to do is seta few variables which decide the month and year to be displayed - these variables will be used throughout the application, and are crucial to it functioning correctly. PHP's date() function is perfect for obtaining this information:

<?
// set up some variables to identify the month, date and year to display
if(!$currYear) { $currYear = date("Y"); }
if(!$currMonth) { $currMonth = date("n"); }
if(!$currDay) { $currDay = date("j"); }
?>

Thus, the variables $currDay, $currMonth and $currYear will hold the values corresponding to the current date, month and year respectively. For example, on 25 January 2001, the variables would look like this:

<?
$currYear = 2001;
$currMonth = 1;
$currDay = 25;
?>

The date() function comes with numerous modifiers which allow you to extract just those specific segments of the date and time you need from a standard UNIX timestamp. This is a feature I'll be using a lot as I begin building my application, so if you're not familiar with it, take a look at the PHP4 date() function reference at before reading further.

Next, it's time to set up some friendly names for the various months of the year and days of the week - these will come in handy when displaying the calendar.

<?
// list of names for days and months
$days = array("Sunday", "Monday", "Tuesday", "Wednesday", "Thursday",
"Friday", "Saturday");
$months = array("", "January", "February", "March", "April", "May", "June",
"July", "August", "September", "October", "November", "December");
// number of days in each month
$totalDays = array(0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31);
// if leap year, modify $totaldays array appropriately
if (date("L", mktime(0,0,0,$currMonth,1,$currYear)))
{
$totalDays[2] = 29;
}
?>

Yup, the date() function even lets you find out if the year under consideration is a leap year - if it is, it's necessary to modify the $totalDays array for the month of February. Since the date() function only works on a correctly-formatted UNIX timestamp, the mktime() function is used to first convert the numeric month and year into an acceptable format.

Before getting into the calendar display, there's one more thing needed: the day of the week on which the first of the month falls.

<?
// find out which day the first of the month falls on
$firstDayOfMonth = date("w", mktime(0,0,0,$currMonth,1,$currYear));
?>

The first day of the month (from the $firstDayOfMonth variable) and the last day (from the $totalDays array) provide the bounding values for the month view I'm going to be building.

This article copyright Melonfire 2001. All rights reserved.

>>> More PHP Articles          >>> More By Vikram Vaswani, (c) Melonfire

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