PHP

Validate EAN13 Barcodes philipnorton42 Thu, 04/30/2009 - 08:31

EAN13 barcodes are commonly used to label products in Europe. If you want to know more about how they work then please view the Wikipedia entry on European Article Numbers.

EAN13 barcodes are actually 12 digits long and are validated by using a check digit, which is placed at the end, making the code 13 digits long. The check digit is worked out by the following process:

Hide And Unhide Code With PHP

If you are selling a system the last thing you want is for people to copy the system and pass it on for free. There are numerous ways to implement parts of the system that will stop this from happening.

By far the easiest is to create a section of code that is hidden, the removal of which will cause the application to fall over. It could even be as simple as a link back to your site so that even if you give you application away for free, you will always have that link present.

Reading And Writing To Compressed gzip Files

Reading and writing to compressed gzip files can be done in much the same way as reading and writing normal files. The main difference is the use of some special functions that compress and uncompress the data. Rather then use fopen() to open a file, you open a compressed file with gzopen(). This is the case for many of the file access functions, although you should be aware that they don't all work exactly the same as each other.

Ping A Website Using PEAR's Net_Ping

Net_Ping is a PHP wrapper for the ping program and provides a neat way pinging a host or checking if a site is up and running. To install it you just need to have pear installed. Once that is done you can do a search for PEAR Net_Ping by opening a terminal and typing:

> ping search ping

This will return the following:

Redirect From HTTPS To HTTP Using PHP philipnorton42 Fri, 04/17/2009 - 15:28

If you have a site with parts of it using SSL, but want to turn it off for mundane pages like the blog section then use the following code. This uses the $_SERVER['HTTPS'] variable to see if HTTPS is turned on, if it is then a header is issued and the page redirected.

PHP Function To Detect A Prime Number

A prime number is a number which has exactly two distinct number divisors: 1 and itself. So if you take the number 11, it can only be divided to get a whole number if it is divided by 1 or 11. If any other number is used then a fraction is always found.

The following function uses a method called trial division to detect if a number is prime or not.

PHP TestFest 2009

PHP TestFest 2009 is a series of events that you can go to and learn how to test PHP and make new friends and contacts in the PHP community.

PHP Script To Select A Person To Make The Tea

In any office there can be arguments about who will make the next round of tea. The following script will allow you to randomly pick a person who is going to make the tea. Rather than have a script that did this once and threw away the information I thought it would be a good idea to use cookies to save the form data for the next time you want to pick a person to make the tea. This is a good exercise if you are trying to understand how cookies work.

First, we will need to variables, the first is an array of people and the second is the number of people in the office.

XML Sitemap Date Format In PHP

To format the current timestamp in W3C Datetime encoding (as used in sitemap.xml files) use the following parameters.

PHP Cryptographic Functions For Passwords philipnorton42 Fri, 03/27/2009 - 23:30

There are three available cryptographic functions in PHP, these are md5(), sha1() and crc32(). All of the functions take a string and output a value that is encrypted and can't be reversed to the original string. In fact the only way to get the original string back is to run a brute force algorithm which tries to guess what the original string was.

To test these functions I will use the following string.

Subscribe to PHP