In this tutorial, we look at creating calendars in PHP. In this first of 4 tutorials, we build a simple, but working calendar for display purposes, looking at the techniques involved. In the second part we'll going to build a more advanced calendar that can display events for each day and has customised styling.

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Overview

Table of Content:

• Creating Calendars in PHP
• The PHP Date() Command
  • Overview
  • This returns the date in the format Sunday, 12^th October 2003 for example
  • Useful tokens
• Building the Calendar
  • Displaying the current month
    • Creating the HTML
    • Creating the PHP
    • Formatting Tip
    • The Calendar Output
• Summary

In this tutorial, we're going to look at creating calendars in PHP. In this first part of the series we build a simple calendar for display purposes, looking at the techniques involved. In the second part we'll build a more advanced calendar that can display events for each day for example and has customised styling.

As well as being useful, calendars use a number of different programming techniques, which can be utilised in many other areas. We'll also look at the best ways to work with times and dates, and how to findthe number of days in a month, or what weekday a date fall on for example.

The most important command when building calendars is the PHP date() command, so let's look at this first.

The PHP Date() Command

Overview

The PHP date() command is incredibly useful, due to the different data that it can return. Although we'll look at some of the functions here, for a full overview of the command its well worth checking out the command in the online PHP manual at http://www.php.net/manual/en/function.date.php

The format for the date() command is:

date($dateFormat, (optional timestamp))

$dateFormat contains a string containing tokens which tell the date command which information to return. Optional timestamp is a UNIX timestamp which represents the date that you want to work with; if it's not given then the date command will automatically work with the current date. As well as working with dates, the date() command can also work with times.

As an example of how the date() command is used, we'll look at a few examples:

<?php echo date("m/d/Y"); ?>

This returns the current date in the format mm/dd/yyyy e.g. 10/12/2003

<?php echo date("l, jS F Y"); ?>

This returns the date in the format Sunday, 12^th October 2003 for example

<?php echo date("G:i"); ?>

This returns the time in the format 19:06 for example

<?php echo date("h:i a"); ?>

This returns the time in the format 7:06 am

You can see that the date() command is extremely versatile, and allows you to create times and dates in many different formats. It can also return other useful information such as the number of days in the current month, the current day of the week, whether it's a leap year etc. All of these come in extremely useful when creating a calendar, and saves a lot of manual coding.

Now let's look at some of the tokens that we are going to be using.

Useful tokens

Because there are over 30 tokens available, we won't look at them all here. Instead, we'll look at a selection of the most useful tokens, and the ones were going to use to build our calendar. To see a complete list of all the tokens (which is well worth printing out for reference), see the online PHP manual at: http://www.php.net/manual/en/function.date.php

Token	Description	Example of Output
d	Day of the month, 2 digits with leading zeros	01 - 31
D	3 Letters representing the day	Mon – Sun
F	Month Name	January – December
h	Hour with leading zeros	01 – 12
H	Hour in 24 Hour Format	00 – 23
i	Minutes	00 – 59
j	Day	1 – 31
l	Day of the week	Sunday – Saturday
L	Whether it's a Leap Year	0 = no, 1 = yes
m	Month Number	1 – 12
M	Month Name	Jan – Dec
t	Number of days in month	28 - 31
w	Number representing day of week	0 = Sunday – 6 = Saturday
W	ISO-8601 Week Number (weeks start on Monday)	E.g. 34
y	Year (2 digits)	99 or 03
Y	Year (4 digits)	1999 or 2003
z	Number representing Day of the Year	0 - 366

Table 1 – Useful date tokens

Note that the case of the tokens is important, and a lowercase letter and the same uppercase letter can represent two different formats. You can also have several different tokens in the same string.

If you include any characters in the token string that aren't actually tokens, these tokens will be left unchanged so you can use them for adding your own formatting to the output. For example, if you wanted the current date in the MySQL date format (yyyy-mm-dd) then you could use:

<?php echo date("Y-m-d"); ?>

This would output 2003-12-10 for example, and you can see that the hyphens (-) have been left unchanged and are included in the output. Any non token characters can be used e.g.

<?php echo date("m/d/Y"); ?>

would output 10/12/2003 for example.

Now that we've looked at how the date() command is used, and at the tokens we have available we can move on and start looking at building a calendar.