PHP eBook

O'reilly -PHP Cookbook - Examples And Solutions

Web programming is probably why you’re reading this book. It’s why the first version

of PHP was written and what continues to make it so popular today. PHP makes

it easy to write dynamic web programs that do almost anything. Other chapters

cover various PHP capabilities, like graphics, regular expressions, database access,

and file I/O. These capabilities are all part of web programming, but this chapter

focuses on some web-specific concepts and organizational topics that will make your

web programming stronger.

Recipes 8.1, 8.2, and 8.3 show how to set, read, and delete cookies. A cookie is a

small text string that the server instructs the browser to send along with requests the

browser makes. Normally, HTTP requests aren’t “stateful”; each request can’t be

connected to a previous one. A cookie, however, can link different requests to the

same user. This makes it easier to build features such as shopping carts or keep track

of a user’s search history.

Recipe 8.4 shows how to redirect users to a different web page than the one they

requested. Recipe 8.5 explains the session module, which lets you easily associate

persistent data with a user as he moves through your site. Recipe 8.6 demonstrates

how to store session information in a database, which increases the scalability and

flexibility of your web site. Discovering the features of a user’s browser is shown in

Recipe 8.7. Recipe 8.8 shows the details of constructing a URL that includes a GET

query string, including proper encoding of special characters and handling of HTML

entities.

The next two recipes demonstrate how to use authentication, which lets you protect

your web pages with passwords. PHP’s special features for dealing with HTTP Basic

authentication are explained in Recipe 8.9. Sometimes it’s a better idea to roll your

own authentication method using cookies, as shown in Recipe 8.10.

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