PHP

The UK PHP TestFest this year was held at MadLab in Manchester on the 11th September. I was one of the 12 people who went along to learn about testing the PHP language. So I thought that I would collate some of the things that we went through during the session.

Before creating a test you need to set up your testing environment, you can do this by going to the TestFest site and running through the tutorial on setting up your system for testing PHP. When you have finished setting up your test environment you will have a folder containing three folders, these are php52, php53 and php-trunk, these are the different versions of PHP which you can test, although we will be concentrating on the php53 version in this article the same practices can be used for the other trunks.

When displaying images added by users it is quite often necessary to resize them in order that they fit into a specific area of the page. Not doing this can cause problems with the images breaking the page layout. The trouble is that if you resize the image absolutely you tend to squash and distort it.

The following function can be used to calculate the width and height of an image to the correct aspect ratio, which will preserve the contents when printed out. This function makes use of the getimagesize() function, which is available as part of the GD library in PHP.

Different functions and options are always being added to PHP. Although new versions generally don't create much backward compatibility issues it is usually prudent to write production code that you know will work on servers running a slightly older version of the language.

To check the currently used PHP version you can use the function phpversion() or the constant PHP_VERSION. Both the function and the constant return a string that contains the version number. There are a couple of ways in which this information can be used, the first is to take the string and convert into an array using the explode() function. With this array you can then check the minor version number and run code like the following:

I quite often find the need to extract a section of text from the beginning of a blog post or similar to be used as the excerpt. I normally use a function that will count the number of whole words available and return the string containing those words.

A good alternative to this, although only applicable if the original post is in HTML, is to use a regular expression to extract the contents. The following code will take a string and extract just the first paragraph of text.

If you need to know the month from a given integer (from 1 to 12) then you can use the following snippet. This will return the string "Feb".

date("M", mktime(0, 0, 0, 2));

This can be encapsulated into a function call that will take a number between 1 and 12 and return the corresponding string for that month. This function includes some simple error checking to make sure that the number is valid before trying to work out the date.

function getMonth($month) 
{
  if (!is_numeric($month) && $month  1 && $month > 12) {
    return false;
  }
  return date("M", mktime(0, 0, 0, $month));
}

Richard Wiseman is a psychologist, magician, and author who runs a little blog over at http://richardwiseman.wordpress.com/. His blog talks about all sorts of things, but every Friday he posts a little puzzle that you can have a go at solving.

The last puzzle posted talked about palindromic numbers and speed, here is the puzzle in full.

The other day I went for a bike ride. My favourite route has signs every meter saying how far you have travelled. I came across the sign saying '15951 meters' and thought 'Oh, that's interesting, it is a number palindrome because it reads the same from left to right as right to left'. Then I rode on. Two hours later I came across the next palindromic number sign. How fast was I going?

Removing the last line from a file is an easy process and can be done in just a few lines of code.

XML data extraction can be a common task, but to work directly with this data you need to understand how PHP parses XML. There are various different functions involved in parsing XML in PHP, all of which work together to extract data from a XML document. I will go through each of these functions and tie them together at the end.

xml_parser_create()

This function is used to create the parser object that will be used by the rest of the process. This object is used to store data and configuration options and is passed to each of the functions involved.

$xml_parser = xml_parser_create();

xml_set_element_handler()

Next we need to set up the functions that will be used in the parsing of the script. The xml_set_handler() method takes the following parameters:

If you want to create a "rounded" time stamp, for example, to the nearest 15 minutes use this as a reference:

Converting an IP address into some useful location information can be useful if you want to find out where sites are hosted or customise content to users depending on their location.

All this code is freely available over at github.

There are several ways to do this, all of which have their advantages and disadvantages, but sticking with one can cause rewriting a lot of code in the future. So rather than pick one and stick with it I decided to use dependency injection to allow different classes to be used that convert IP addresses to locations in different ways. The first task is to create an abstract class that will be used to construct the rest of the IP location classes. Each class that extends this abstract class will contain a method called getIpLocation() that will convert an IP address into a location, and a method that will update the data source for the location lookup. Rather than lump all of the classes into a single directory I have created a directory called Service, into which all of the different classes that lookup IP addresses will be kept.