Beginning PHP 5.3

Chapter 6. Arrays

In Chapter 3, you learned about variables in PHP; in particular, you learned that a variable is a container that can store a single value. However, a couple of types of variables can store many values at once within a single variable. One such type is an object, which you discover in Chapter 8; the other type is an array, which you explore in this chapter.

Arrays are a very powerful feature of any programming language, because they let you easily work with large amounts of similar data. For example, say you are writing a script that stores information about 100 customers. Rather than having to create 100 separate variables — $customer1, $customer2, and so on — to store the customers, you can create just one array variable called $customers that holds information on all the customers at once.

Two specific features of arrays make them good for storing lots of data:

• Arrays can be of any length — An array can store one value, or millions of values, all referenced via a single variable name (for example, $customers). What's more, you can easily change the length — by adding or removing values — at any time

• It's easy to manipulate all values in an array at once — For example, you can loop through all the values inside an array, reading or changing them as you go. You can easily sort an array in any order you like. You can search for a value in an array, merge two arrays together, and much more

In this chapter, you:

• Learn how PHP arrays work

• Look at different ways ...