Learning PHP, MySQL & JavaScript, 5th Edition

Chapter 6. PHP Arrays

In Chapter 3, I gave a very brief introduction to PHP’s arrays—just enough for a little taste of their power. In this chapter, I’ll show you many more things that you can do with arrays, some of which—if you have ever used a strongly typed language such as C—may surprise you with their elegance and simplicity.

Arrays are an example of what has made PHP so popular. Not only do they remove the tedium of writing code to deal with complicated data structures, but they also provide numerous ways to access data while remaining amazingly fast.

Basic Access

We’ve already looked at arrays as if they were clusters of matchboxes glued together. Another way to think of an array is like a string of beads, with the beads representing variables that can be numbers, strings, or even other arrays. They are like bead strings because each element has its own location and (with the exception of the first and last ones) each has other elements on either side.

Some arrays are referenced by numeric indexes; others allow alphanumeric identifiers. Built-in functions let you sort them, add or remove sections, and walk through them to handle each item through a special kind of loop. And by placing one or more arrays inside another, you can create arrays of two, three, or any number of dimensions.

Numerically Indexed Arrays

Let’s assume that you’ve been tasked with creating a simple website for a local office supply company and you’re currently working on the section devoted to paper. ...