TechTip: Meet Your New PHP Friends, Mrs. date and Mr. strtotime PDF Print E-mail
Tips & Techniques - Web Languages
Written by Jan Jorgensen   
Friday, 15 January 2010 00:00

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It's not RPG, but still, PHP has some strong date functions.

Written by Jan Jorgensen

PHP gets more and more hot in the IBM i community, so I'm planning a series of TechTips about PHP functions that you might find useful.

 

My tips will be created the following way. First, I will give a short intro to the PHP function(s) and provide a link to the PHP manual. Then, I'll show you some working code examples that you can download and change to suit your needs. Or you can just play with the code to see how it all works.

 

You'll need to have access to a PHP environment. If you don't already have that, read my article about how to install Apache and PHP locally on your own PC.

 

The tips will be pretty brief, and the code examples will be easy to implement, so you should be able to use these tips as a dessert after your lunch break.

 

So with that in mind, let's set off and meet your new friends.

 

Time in PHP is not the same as you are used to in RPG. Let me start by saying that. So before you start shaking your head in agony, give it a chance and flow with it. PHP has no native date/time types as we know them from RPG.

 

PHP is based on Unix (or POSIX) time, which ranges from January 1, 1970 00:00:00 UTC to January 19, 2038 03:14:07 UTC.

 

The Unix time is represented in a 32-bit signed integer, and a wraparound will occur at this date. Read about the Year 2038 (Y2K38) problem here. This means that 2010-01-01 will be represented as the number 1262300400. If you try to hit the number 1, you have to take into account where you are in the world and how your PHP is configured. Here in Denmark, where I live, 1970-01-01 01:00:01 will give me the digit 1, and 2038-01-19 04:14:07 will give me 2147483647, which is the highest number before the wrap.

 

With that in mind, let's start looking at the two functions that I will present for you today.

Meet Mr. strtotime and Mrs. date

The PHP.Net manual states that strtotime will "parse about any English textual datetime description into a Unix timestamp." This means that you can create a line like strtotime("10 September 2000 + 5 days + 15 years") to get the number 1757887200. If you pass strtotime("2009-12-27 last Friday"), you will get1261695600. Pretty cool, huh?

 

I can imagine the look on your face. You're wondering, is he nuts? What the heck can I use that for? Well, meet Mr. strtotime's 18 carat love affair, the one and only Mrs. date.

 

The PHP.Net manual states that date will "format a local time/date." This means that you can convert  an integer given by strtotime into a date. You can also format a date into another date format, a weekday, or something else that has the "form or shape" of a date. Well, that makes sense.

 

In the date manual, you can see that to get the 4-digit representation of the year, you have to use the letter Y. To get the numeric representation of a month with leading zeros, you have to use the letter m, and to get the day as a numeric representation with leading zeros, d is the letter to use.

 

So to make PHP print out the current date, the code would look like the line below:

 

echo date('Y-m-d');

 

Or to store the date in a variable, you would do this:

 

$curDate = date('Y-m-d');

echo "Current date is: $curDate";

 

Now, if you want the month in text, just change the code to this:

 

$curDate = date('Y-F-d');

echo "Current date is: $curDate";

 

And if you want to know how many days are in the current month, the code would look like this:

 

echo "Number of days in " .  date('F') . " is " . date('t');

 

Now, don't tell me that isn't cool!

 

OK. Now, let's combine date with strtotime and try to wrap up the examples from before and see what we get from the two previous examples:

 

The following code will give us 2025-09-15:

 

date('Y-m-d',strtotime("10 September 2010 + 5 days + 15 years"))

 

And this will give us 2009-12-25:

 

date('Y-m-d',strtotime("2009-12-27 last Friday"))"

 

Below are some more examples you can play around with:

 

echo "<br>";

$date = '2010-01-19';

echo date('d-m-Y',strtotime("$date")), "<br>";

echo date('Y-m-d H:i:s',strtotime("now + 15 days + 5 hours")), "<br>";

echo date('Y.m.d',strtotime("10 September 2000 + 5 days + 15 years")), "<br>";

echo date('Y-m-d H:i:s',strtotime("+1 day")), "<br>";

echo date('Y-m-d',strtotime("+1 week")), "<br>";

echo date('Y-m-d H:i:s',strtotime("+1 week 2 days 4 hours 2 seconds")), "<br>";

echo date('Y-m-d',strtotime("next Thursday")), "<br>";

echo date('Y-m-d',strtotime("last Friday")), "<br>";

echo date('Y-m-d',strtotime("2009-12-27 last Friday")), "<br>";

 

Or download the example from here.

 

Finally, I have created a small example in which you select an order date for an album, and the program will calculate the delivery date using the PHP functions I have described in this TechTip.

 

Because of the lack of space, I am not including all the PHP code here. You can download the example code here. Unzip it somewhere in your document root and load the PHP script like shown:

 

http://localhost/...../deldate/delivery.php

 

The interface looks like the one in Figure 1:

 

011510Jorgensen1

Figure 1: Pick an album and an order date to generate a delivery date.

As Time Goes By

Are you beginning to see the picture? Both Mrs. date and Mr. strtotime are very flexible, and you can do amazing things with them—the perfect marriage you might say. I'll let you judge for yourself. Take a look at my examples. If you're not impressed, you'll have to wait for my next tip, where I'll give it another try with some more PHP functions.

 

I encourage you to email me suggestions for TechTips about PHP functions you have used that you feel would be helpful to the rest of us.

 

 


Jan Jorgensen
About the Author:

Jan Jorgensen is one of the owners of www.reeft.dk, which specializes in mobile and i5 solutions. He works with RPG, HTML, JavaScript, Perl, and PHP. You can reach him at here.

 

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Last Updated on Friday, 15 January 2010 00:00
 
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