PEAR version 1.0 was released in tandem with PHP version 4.3.0. Since then, the PPM and PFC have been included in all default installations of PHP, with exception of the version of PHP installed under Windows through use of the automatic installer. Typically, there is no need to perform a separate ... [More]

Simply put, PEAR is the PHP Extension and Application Repository. The PEAR website defines it as "a framework and distribution system for reusable PHP components." Yet, over the years PEAR has evolved into something more than just a library of PHP classes. Other PHP code and class directories exist,... [More]

With the basics of sessions out of the way, let's examine exactly how sessions work by customizing how sessions are handled internally. By default, PHP provides three internal methods of storing session data specified by session.save_handler: the internal PHP session file format (specified by php), ... [More]

One of the most useful applications of cookies is the capability to create sessions, which truly allow you to overcome the state-less nature of the HTTP protocol. When working with sessions in PHP, you are given the capability to store variables (including arrays and classes) between script execut... [More]

Although quite useful as a protocol, HTTP is known in the computer science world as a "stateless" protocol. If that doesn't make sense to you, don't worry. Unlike your favorite programs that you run on your desktop, such as a word processor, PHP has no way of remembering a past request. The only i... [More]

Anytime you are working with HTML forms, using some method or another you have to deal with processing that form. Often, not only does the form have to be processed (meaning you have to do something with the form data), but it almost always has to be validated in some fashion. In fact, it is stron... [More]

In this section I'll discuss methods you can use to protect data passed in HTML forms. Often when you're working with forms, it is necessary to pass data in the form of hidden input tags. For instance, let's assume that a form that you are working on requires that the user submits it back to the ser... [More]

A common problem when working and displaying form data can be traced to what is usually considered a nicety in PHPmagic quotes. When you're working with data external to PHP (whether from a form submission or a database), PHP can automatically add an escape character (backslash) to any characters, w... [More]

Perl Compatible Regular Expressions (PCRE) are much more powerful than their POSIX counterpartsand consequently, also more complex and difficult to use PCRE adds its own character classes to the extended regular expression rules that we saw earlier: \w represents a "word" character and... [More]

The regular expression standard that made its way through the POSIX standard is perhaps the simplest form of regex available to PHP programmers. As such, it makes a great learning tool because the functions that implement it do not provide any particular "advanced" features. In addition to the stan... [More]

Even though regular expressions are quite powerful because of the original rules, inherent limitations make their use impractical. For example, there is no regular expression that can be used to specify the concept of "any character." In addition, if you happen to have to specify a parenthesis or st... [More]

Regex is, essentially, a whole new language, with its rules, its structures, and its quirks. You'll also find that your knowledge of most other programming languages will have practically no bearing on learning regex, for the simple reason that regular expressions are highly specialized and follow t... [More]

If strings are nothing more than a collection of characters to a computer, to a human being they often represent concepts and data that are best presented following certain conventions. Even when dealing with computers, however, it's sometimes necessary to ensure that the contents of a string follow... [More]

Date and time values are always quite difficult to deal with, and not only from a representation point of view. Because the Universe refuses to work on multiples of ten, and the measurement of time that we take for granted is not exactly that accurate, calculating the difference between two dates is... [More]

Using strings without being able to tell what's inside them is a bit like driving around at night with your headlights offyou know the road might be there, but you can't really tell. PHP offers a wide array of functions for searching and replacing text inside strings using both the traditional "mat... [More]