Page 139 - Beginning PHP 5.3

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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 of creating arrays
❑ Discover how to access the elements of an array

❑ Find out how to use loops (which you studied in Chapter 4 ) to work your way through all
the elements of an array

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