Common Regular Expressions

24th March 2008 - 2 minutes read time

Here are some of the regular expressions that I frequently use.

Find a blank line



[ \t]+

You can use this to break a text string apart into words.



This will match anything in the format mm/dd/yyyy, or even dd/mm/yyyy.

[A-Z][a-z][a-z] [0-9][0-9]*, [0-9]{4}

Will match a formatted date, such as Mar 24, 2007.



This will match HH:MM or HH:MM:SS or HH:MM:SS.mmm.

IP Address

Read the full article The Regular Expression Library

22nd March 2008 - 3 minutes read time

Writing regular expressions can sometimes be a real pain, especially if you are not used to them. Rather than trying for yourself to make a regular expression you might want to think about looking for regular expressions that other people have made. Rather than reinventing the wheel to prove you can do something,using free third party regular expressions can save you a lot of time.

The RegExLib or regular expression library is a great resource for finding any regular expression that you are looking for. The Regular Expression Library

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reWork: A Regular Expression Workbench

21st March 2008 - 3 minutes read time

Regular expressions are a very useful tool for any programmer wanting to validate input, format strings, change words, reformat data or even split apart a string into an array. However, when you are starting out, writing them it can be hard going, they are not very easy to learn and the only way to really understand them is to practice, practice, practice.

This is where reWork steps in. It is a fully functional online regular expression workbench that will allow you to plug the expression and the text in one end, and it will show you exactly what is being matched. This simple JavaScript program is far better than any stand alone application I have seen and has more functionality than you could even think about.

reWork: Regular Expression Workbench

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Save Browser Output To A File With PHP Output Buffering Functions

19th March 2008 - 6 minutes read time

The PHP output buffering functions provide a handy way of intercepting the contents of the buffer before it is sent to the browser. The output is whatever is sent to the browser whenever you print something off. PHP allows you to capture this output in a buffer before it is sent to the browser.

Output buffering is controlled by two mechanisms. The first is through the php.ini directive output_buffering, which is usually set to off. It can be turned on by setting this to either on, or the number of bytes that the buffer can take up. When this byte allocation is full the output is sent to the browser.

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A Garbage Collection Mechanism In PHP

18th March 2008 - 3 minutes read time

Garbage collection is a term for a maintenance function in a class or script that you don't want to run every time the script is run.  The main function of the script is to clean up anything that the script has used previously, but is now not important in the general running of the system and can be removed with no ill effects.  However, it is important that the garbage collection is not run every time the script is run as it may have a detrimental effect on the speed of the system.  To get around this we can use a random number generator to generate a number within a range, and use this to test if the garbage collection function should be run.  Here is the code.

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17th March 2008 - 3 minutes read time

By far the best resource for finding information about PHP and all of the functions available is from the PHP website. Not only can you view the PHP documentation, but you can also download PHP and many of the extensions like the Smarty template system.

Each PHP function and section has its own page with lots of detailed information about usage and instillation, which can be found quite easily on the site by entering the domain name followed by the function name you want to look up. If the function isn't found that the site points you towards a search results page.

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PHP5 Filter Functions Part 2

15th March 2008 - 6 minutes read time

Following on from the previous post about the PHP filter functions there are two more filter functions that require some extra explanation. These functions are filter_var_array() and filter_input_array().

They work in much the same way as filter_var() and filter_input() but they accept an array as the input. This enables you to sanitize or validate many different variables at the same time.

The first step in using these functions is to create an argument array. This is an associative array of data identifiers that allow you to set filter and sanitizer flags for different values. For example, assume that the following array is going to be used.

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PHP5 Filter Functions Part 1

14th March 2008 - 5 minutes read time

The filter functions are part of the PECL library and should come as standard on most PHP 5 installs. If they aren't there then ask your server administrator to install them.

The filter functions where created to avoid developers having to write lots of unmaintainable code in order to check the validity of variables and to sanitize these variables once validated. So rather than using many different functions and regular expressions to tell if a value is a number, a boolean or even a URL, you can just use these filter fucntions.

The main functions that you might be interested in are filter_var() and filter_input(). The filter_var() function is used to validate a single input, the parameters are:

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