PHP

Creating image thumbnails is a pretty common practice, and there are a few scripts available that allow you to do this in PHP using the GD2 library. However, they are normally overkill for what should be a simple task, so after a bit of searching and testing I found the following ImageResize class, which is taken from http://shiege.com/scripts/thumbnail/. I have modified the code to be PHP5, but if you want the PHP4 version then you can get it from the site.

I have talked previously about getting an IP address of a visitor with PHP. The failing in using the value of $_SERVER["REMOTE_ADDR"] is that if the visitor is using a proxy then you will get the proxy IP address and not the visitors real IP address.

This function works by going through any variables in the $_SERVER array that might exist that would contain information to do with IP addresses. If they are all empty then the function finally looks at $_SERVER["REMOTE_ADDR"] value and returns this as a default.

I have been asked a couple of times recently if PHP has a function that will move a file, so I thought I would put the solution here.

PHP has a function called rename() which can be used to rename a file, but because of the way it works it can be used to move files. Let's say that you wanted to rename a file called test.txt to test_back.txt, this can be accomplished by doing the following.

rename("test.txt", "test_back.txt");

However, if you want to move the file from one directory to another you can do the following.

rename("test.txt", "backups/test_back.txt");

The return value of rename() is boolean that tells you if the rename was successful or not, this can be used to error check like this.

File permissions are important, especially if you want to let a user agent view a file. If the file doesn't have the correct permissions then it will not be accessed and could cause your script to fail. To get around this you might want to use the following function. It uses the PHP function chmod(), which sets permissions, but it does this recursively from wherever you set it off from.

I have talked about swapping values without a temporary third variable before, but there is another way to do this which doesn't make the code unreadable. This is by using the list() function in the following way.

$a = 1;
$b = 2;
list($a,$b) = array($b,$a);

This swaps the two values over. The good thing about this function is that you can swap any number of values over without the need to create lots of confusing temporary variables or using complicated looking bitwise operators. Take 4 variables.

$a = 1;
$b = 2;
$c = 3;
$d = 4;

These values can be entirely swapped using the list() function in the following way.

NOTE: This bit of code is potentially very dangerous and should NOT be uploaded to your web host. I only use this function on my localhost to quickly check that a snippet of code works.

If you want to quickly run some PHP code, and don't want to have to go through creating a file just to see the outcome of a simple calculation is then this snippet might be of some use to you.

It works by taking the contents of the textarea and creating a file with the filename of 'tempcodefile.php', which contains that code. The created file is then included in order to run the code, the output of which is displayed at the top of the screen.

Yesterday I wrote two posts about CodeSniffer and a common warning that I couldn't find any decent documentation on. I thought that today I would go over something that I also had trouble finding out about, this is the file doc error. When you run CodeSniffer on a class you might find the following error being produced.

In my last post I talked about the PHP CodeSniffer, so today I thought I would solve a common problem that doesn't seem to have any documentation. Whilst correcting a class file I had there was this one warning that just wouldn't go away.

FILE: myclass.php
--------------------------------------------------------------------------------
FOUND 0 ERROR(S) AND 1 WARNING(S) AFFECTING 1 LINE(S)
--------------------------------------------------------------------------------
 11 | WARNING | PHP version not specified
--------------------------------------------------------------------------------

There is no documentation (that I could find) on the CodeSniffer site about how to solve this, so I dove into the source files for the CodeSniffer extension and found this line.

One of the biggest problems I have found with PHP is the reputation that it gets. This is due to the amount of abuse that the language undergoes by many developers every day. They write code that works, and is efficient, but trying to figure out what it does can take hours as there are no comments, and the code is generally written in any old way. PHP is quite lenient with regards to how code is written.

This is where CodeSniffer comes in. CodeSniffer is a PHP5 script that goes through any PHP (or JavaScript) file that you give it and detects coding violations from a defined set of coding standards. These standards start out with the simple things like using spaces instead of tabs (due to the way in which tabs are displayed differently on different computers) to the more complex things like prefixing private variables with an underscore.

There are two ways to find out the number of days for a given month. The first is to use the date() function in conjunction with the mktime() function to create a date and format this value as the number of days in a given month.

$monthDays = date("t",mktime(0, 0, 0, 12, 1, 2008));

The second way is to use the function cal_days_in_month(). This function takes three parameters.