Specifications

Using PHP

ART I

This chapter shows you how to use an important programming construct—arrays. The vari-

ables that we looked at in the previous chapters are scalar variables, which store a single value.

An array is a variable that stores a set or sequence of values. One array can have many ele-

ments. Each element can hold a single value, such as text or numbers, or another array. An

array containing other arrays is known as a multidimensional array.

PHP supports both numerically indexed and associative arrays. You will probably be familiar

with numerically indexed arrays if you’ve used a programming language, but unless you use

PHP or Perl, you might not have seen associative arrays before. Associative arrays let you use

more useful values as the index. Rather than each element having a numeric index, they can

have words or other meaningful information.

We will continue developing the Bob’s Auto parts example using arrays to work more easily

with repetitive information such as customer orders. Likewise, we will write shorter, tidier

code to do some of the things we did with files in the previous chapter.

Key topics covered in this chapter include

• What is an array?

• Numerically indexed arrays

• Associative arrays

• Multidimensional arrays

• Sorting arrays

• Further reading

What Is an Array?

We looked at scalar variables in Chapter 1, “PHP Crash Course.” A scalar variable is a named

location in which to store a value; similarly, an array is a named place to store a set of values,

thereby allowing you to group common scalars.

Bob’s product list will be the array for our example. In Figure 3.1, you can see a list of three

products stored in an array format and one variable, called

$products, which stores the three

values. (We’ll look at how to create a variable like this in a minute.)

Tires Oil

product

Spark Plugs

IGURE 3.1

Bob’s products can be stored in an array.

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