Beginning PHP 5.3

Chapter 4. Decisions and Loops

So far, you've learned that PHP lets you create dynamic Web pages, and you've explored some fundamental language concepts such as variables, data types, operators, expressions, and constants.

However, all the scripts you've written have worked in a linear fashion: the PHP engine starts at the first line of the script, and works its way down until it reaches the end. Things get a lot more interesting when you start introducing decisions and loops.

A decision lets you run either one section of code or another, based on the results of a specific test. Meanwhile, a loop lets you run the same section of code over and over again until a specific condition is met.

By using decisions and loops, you add a lot of power to your scripts, and you can make them truly dynamic. Now you can display different page content to your visitors based on where they live, or what buttons they've clicked on your form, or whether or not they're logged in to your site.

In this chapter you explore the various ways that you can write decision-making and looping code in PHP. You learn about:

• Making decisions with the if, else, and switch statements

• Writing compact decision code with the ternary operator

• Looping with the do, while, and for statements

• Altering loops with the break and continue statements

• Nesting loops inside each other

• Using decisions and looping to display HTML

Once you've learned the concepts in this chapter, you'll be well on your way to building useful, adaptable PHP scripts. ...