"Extending PHP" is easier said than done. PHP has evolved into an increasingly mature tool with source code packages tens of megabytes in size. To hack such a complex system, you have to learn and think. When constructing this chapter, we ultimately chose a “l(fā)earning by doing” approach. This is not the most scientific or professional way, but it is the most fun and gives the best end result. In the following sections, you will quickly learn how to get the most basic extensions and have them run immediately. You will then learn about Zend's high-level API features in a way that will have you trying to illustrate (ZEND API-related) functionality, design, suggestions, tips, and more. In a nutshell, this provides a broad overview before any actual combat. Even though this is the "better" approach and does not generate junk hacks, it is difficult, laborious and time-consuming to learn, which is why we decided to use the "learn by doing" approach.

Note that although the content of this chapter attempts to explain as much as possible about the inner workings of PHP, it is not possible to truly give a complete guide to PHP extensions that can be used in every situation at all times. Because the PHP package is so large and complex, when you learn it through actual practice, you can only understand its internal working mechanism. So we encourage you to study along with the source code.