Why PHP DateTime Rocks

Posted: 2012-08-01
Category: PHP

Working as a freelancer and contracter sometimes I come accross some code that is so terrible I have to laugh, then immediately tweet a screenshot for others to laugh. I think this is fairly healthy, but one reaction I get fairly often is "Yuck, PHP!". Really that should be "Yuck, PHP 4!" I've been using PHP since 4.0.1 and I remember it well. It was terrible. Whenever I see these chunks of code I like to see how clean I can make them with PHP 5.3 + code and DateTime has saved me a lot of lines.

DateTime is nothing new, but it's definitely under-used by many. It was made available in PHP 5.2.0 but got some of its best features until PHP 5.3.0. PHP 5.3.0 is pretty old now, but I learned about DateFormat::createFromFormat() after reading a new addition to PHP The Right Way: Date and Time.

Right, down to business.

First Offender

Format one crazy date into the standard MySQL date format.

Yuck. Using DateFormat::createFromFormat() we can ditch all of that code and instead just use this:

That's much better. But how about comparing dates?

Second Offender

Use mktime() to build them both into unix timestamps, then find out how many seconds right?

Did you just throw up in your mouth a little?

This sort of stuff is way too common and is totally unnecessary. If we want to stop pretending it's the 90's we could instead write it like this:

And there we have it!

We have cleaner, more readable, more reliable code. A perfect example of why you need to be upgrading to PHP 5.3 and a perfect example of PHP making massive leaps forward over time.

Update: Some people here and on Reddit are assuming I've never heard of strtotime() before. My mistake here was not being able to for-see EVERY possible angle for the article, which a common problem for bloggers.

So, why not use strtotime()? Firstly, using date('Y-m-d H:i:s', strtotime($strDate)) is the same as doing $date = new DateTime($strDate)->format('Y-m-d H:i:s') but of course with the objects you get more potentially useful methods than just an integer - which can lead to less code. Secondly, read the documentation

Dates in the m/d/y or d-m-y formats are disambiguated by looking at the separator between the various components: if the separator is a slash (/), then the American m/d/y is assumed; whereas if the separator is a dash (-) or a dot (.), then the European d-m-y format is assumed.

To avoid potential ambiguity, it's best to use ISO 8601 (YYYY-MM-DD) dates or DateTime::createFromFormat() when possible.

strtotime() is only useful if it KNOWS the format but what is happening here: 7/7/2011? Is that UK or US, because that could be m/d or d/m. When you are dealing with code that comes in from a wide array of random sources (horrible ADF feeds in this case) then the date formats are MENTAL, and telling it WHAT the data is means it can be parsed correctly.

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