PHP:CSI

I read The Daily WTF every now and then and one story about bad logging code in PHP stood out to me. The post looked at some PHP code that was created to log a string to a file, but would have progressively slowed down the application every time a log was generated.

PHP is a great language as it allows you to put together code without easily shooting yourself in the foot. One downside of this ease of access is that it can allow beginners to put together code that works, but will ultimately cause problems in the long run. The PHP code given in the post is certainly an example of this.

I know that the goal of The Daily WTF isn't to fix problems found in code and is more of a satirical look at bad coding examples. I thought, however, that it would be good to look at the code and fix the issues it had.

I was writing unit tests for a API mapping function recently and came across this interesting issue. The code I was writing tests for was in a legacy codebase that I was making changes to, and it made sense to have some unit tests in there before I started work to ensure everything worked before and after.

The mapping function in question would take a value as input and return another value as the output. The code seemed like it should work, but then applying certain values to the mapping function it would produce an incorrect result.

I was looking at some malfunctioning code the other day where the price was pulled out of one API service and sent to another API. The problem stemmed from the fact that the value coming out of the first API was as a string and the second API required the price in pence as an integer.

The difference in formats here meant that the number had to be converted from one format to another. During this process it was found that the value was sometimes out by a single pence.

For example, whilst the first API sent over a value of £20.40, the second API received a value of 2039, which is one penny out. This class did have some unit tests, but the tests but had failed to account for this rounding error.

As it turned out, this wasn't the only problem with the class in question, so I thought I would write up a quick PHP:CSI showing the problems and how I solved them.

A while ago I was working on some changes to a website and came across a block of code that made me stare blankly at my screen. The website I was working on was a custom build website, created by another developer at the company I was working with at the time. I have never done a PHP:CSI on this site before but remember being so amazed at what I found at the time that I made a note of it for future reference. I have pondered recently how to approach the analysis of the code.

The code I found was in a method that inserted an item into a database table. For some reason that I can't fathom the developer had opted to not use auto increment ID's and has instead developed a method that essentially randomly decided on an ID number for the item.

I can't paste the entire block of code here, but I can include the region of code that made me scratch my head in bewilderment.