Part 3.7Working with dates in PHP

PHP offers a plethora of different date functionalities that make working with dates much easier.

In the most primitive manner, a date is an intthat represents an epoch time timestampEpoch timestampA numeric representation of a millisecond in time since January 1st 1970.

In PHP a date is exactly this, but to form a date that means something to a human, it is first converted to a string.

Timezones

A timezone in PHP represents a timezone in the world. For instance, UTC or Coordinated Universal Time is a timezone in the real world. In PHP the UTC timezone is also a timezone parameter. Another timezone is Europe/London .

Any timezone can be used to represent a real world timezone and all subsequent date representations will be in that timezone, so conversion between different timezones is much easier.

date_default_timezone_set('Europe/London');
		

Now all future dates will be in their 'Europe/London' format.

There are too many different timezones to place in this article, but they can all be found in the PHP manual.

Working with dates

As mentioned before, date in PHP are converted from a timestamp to a string type in order for them to display properly. PHP makes this easy with the date function.

The date function can also be used to represent times. To declare a date in a proper date format, the date function is used as follows:

date ("Day Month Year Hour Minute Second", timestamp);
		

Every parameter of the string is entirely optional for instance, an hour value may be the only one specified to obtain the hour. The timestamp parameter is also optional.

Specifying a timestamp parameter to another date (for instance using the time() function will return the current time) will turn that time into a date of that format. As mentioned before, this is optional and if it is not specified the default value will be the current time (which is the equivelant to calling the time function).

date ("dS F Y g:i:s A");
		

The mktime() function can also be used to generate a time as well which can in turn be passed in to the date function. The mktime function is used as follows:

//Creates a time to the 12th of July 2014 at 13:34:29.
$time1 = mktime (13, 34, 29, 7, 12, 2014);
//Creates a time to the 26th of January 2013 at 9:12:43.
$time2 = mktime (9, 12, 43, 1, 26, 2013);
		

The following parameters are for the day and week parameters of the date function:

The following parameters are for the month value of the date:

The next parameters affect the year parameter of the date:

As mentioned before, times can be represented using the date function: