The first part of this book is a thorough discussion of PHP as a programming language. You will be introduced to common concepts of computer science and how they are implemented in PHP. No prior programming experience beyond the use of simple mark-up languages is necessary. That is, you must be familiar with HTML. These chapters focus on building a foundation of understanding rather than on how to solve specific problems. If you have experience programming in a similar language, such as C or Perl, you may choose to read Chapter 1 and skim the rest, saving it as a reference. In most situations, PHP treats syntax much as these two languages do.
Chapter 1 is an introduction to PHP—how it began and what it looks like. It may be sufficient for experienced programmers, since it moves quickly through PHP's key features. If you are less experienced, I encourage you to treat this chapter as a first look. Don't worry too much about exactly how the examples work. I explain the concepts in depth in later chapters.
Chapter 2 introduces the concepts of variables, operators, and expressions. These are the building blocks of a PHP script. Essentially, a computer stores and manipulates data. Variables let you name values; operators and expressions let you manipulate them.
Chapter 3 examines the ways PHP allows you to control program execution. This includes conditional branches and loops.
Chapter 4 deals with functions, how they are called and how to define them. Functions are packages of code that you can call upon repeatedly.
Chapter 5 is about arrays—collections of values that are identified by either numbers or names. Arrays are a very powerful way to store information and retrieve it efficiently.
Chapter 6 is about classes, presenting an object-oriented approach to grouping functions and data. Although not strictly an object-oriented language, PHP supports many features found in OO languages such as Java.
Chapter 7 deals with how PHP sends and receives data. Files, network connections, and other means of communication are covered.
