There is a book called PHP Architect's Zend PHP 5 Certification Study guide. If you get lucky, you will probably find it online as PDF file..From PHP 5 release of 2004, PHP is powered by the new Zend Engine II. Meaning all coding standards are govern by the Zend Engine. Although there are some backward compatibilities reserved for some of the residues of PHP4, PHP 4 is no longer updated.
The reason I am telling you this, just in case you bumped into php4 documentations that were also released by the same organization prior to 2004.
Now, that I laid out some of the important aspects about PHP, let us talk a little about the reason why, I would recommend PHP Architect's Zend PHP 5 Certification Study guide? My reasonings is that, if you read and research all the topics covered in this book, you will learn lots of things that will help you become a much improved practicetioner of PHP.
Although some of the presented topics and example codes in the book are somewhat questionable, I still believe the book is worth reading.
Read and analyze PHP source codes written by others... all of us can learn from others by analyzing their published source codes. It can be as simple as login script or an entire CMS application.
Learn the logic switch algebra e.g. NOR/OR/AND/NAND/XOR and the rest of it, because it does apply to programming also. Many people would rush-in and diving into programming with very little and no knowledge of at least college level Mathematics. This is a very serious mistakes. The reason is that, how can we refactor something if we don't have no knowledge of what refactor means? How about multi-conditional situations?e.g. we want something to be true, while we also want something to be OR declared in one statement.
People who read the book and PASSED the Zend Engineer Certification with flying colors.
My coffee Drinking Buddies:
1. Veedeoo -- he was the cream of the crop when he took it at the age of 16... ( this kid is madly brainiac)..This is the type of coder that can write an application, before he finishes is cup of coffee.. just an amazing person to be co-developing with higly sophisticated applications and API.
2. Larry Singleton --- He passed, but won't talk about it.
3. Yours Truly.... I better not talk about it, but the book and other books did help me a lot.