Home arrow PHP arrow Page 2 - Using Filters in PHP 5

Filters available in PHP 5 - PHP

You've probably built custom functions and libraries to validate user input in PHP 5. There's an easier way to do this, and it can save you considerable time and effort. It involves using PHP 5's own built-in and often-neglected filters. This nine-part series will introduce you to their use.

  1. Using Filters in PHP 5
  2. Filters available in PHP 5
  3. Checking for integer values with the filter PHP extension
  4. Using the FILTER_VALIDATE_INT filter to check for minimal and maximal values
By: Alejandro Gervasio
Rating: starstarstarstarstar / 8
July 15, 2009

print this article



Before I start explaining how to use filters in PHP 5, it’s convenient to check which of them comes with the PHP distribution. To do this, I’m going to use a pair of handy native functions called “filter_list()” and “filter_id()." The first one will return an array of the existing filters and the second one will retrieve their corresponding IDs.

A simple demonstration of how to use these functions is coded below. Take a look at the following example:



// example on using the 'filter_list()' function

foreach(filter_list() as $id => $filter)


echo '<p> Filter Name: ' . $filter . ' ------------- Filter ID: ' . filter_id($filter) . '</p><hr />';



/* displays the following


Filter Name: int ------------- Filter ID: 257


Filter Name: boolean ------------- Filter ID: 258


Filter Name: float ------------- Filter ID: 259


Filter Name: validate_regexp ------------- Filter ID: 272


Filter Name: validate_url ------------- Filter ID: 273


Filter Name: validate_email ------------- Filter ID: 274


Filter Name: validate_ip ------------- Filter ID: 275


Filter Name: string ------------- Filter ID: 513


Filter Name: stripped ------------- Filter ID: 513


Filter Name: encoded ------------- Filter ID: 514


Filter Name: special_chars ------------- Filter ID: 515


Filter Name: unsafe_raw ------------- Filter ID: 516


Filter Name: email ------------- Filter ID: 517


Filter Name: url ------------- Filter ID: 518


Filter Name: number_int ------------- Filter ID: 519


Filter Name: number_float ------------- Filter ID: 520


Filter Name: magic_quotes ------------- Filter ID: 521


Filter Name: callback ------------- Filter ID: 1024



As you can see in the above code sample, the combined use of the “filter_list()” and “filter_id()” functions provides useful information about the filters that are available with the PHP 5 distribution. In this particular case, the name and ID of each filter is displayed on screen via a simple “foreach” construct, which helps you understand each one's functionality. 

Of course, from the previous example it’s easy to see that there are filters available for checking integers and float numbers, Boolean values and regular expressions, URLs, email and IP addresses, strings and special characters, and so forth. However, since this will be a progressive process, I’m going to discuss  each filter in detail in successive tutorials of this series.

At this point you should have some idea of how useful PHP 5 filters can really be for validating incoming data. Therefore, it’s time to start an in-depth discussion of the first filter shown by the previous list. It is the one responsible for checking whether a given value is an integer.

This brand new PHP 5 filter will be explored in detail in the next segment. Thus, to learn how to work with it, click on the link below and read the next few lines.

>>> More PHP Articles          >>> More By Alejandro Gervasio

blog comments powered by Disqus
escort Bursa Bursa escort Antalya eskort


- Hackers Compromise PHP Sites to Launch Attac...
- Red Hat, Zend Form OpenShift PaaS Alliance
- PHP IDE News
- BCD, Zend Extend PHP Partnership
- PHP FAQ Highlight
- PHP Creator Didn't Set Out to Create a Langu...
- PHP Trends Revealed in Zend Study
- PHP: Best Methods for Running Scheduled Jobs
- PHP Array Functions: array_change_key_case
- PHP array_combine Function
- PHP array_chunk Function
- PHP Closures as View Helpers: Lazy-Loading F...
- Using PHP Closures as View Helpers
- PHP File and Operating System Program Execut...
- PHP: Effects of Wrapping Code in Class Const...

Developer Shed Affiliates


Dev Shed Tutorial Topics: