Chapter 1. Introduction to PHP
PHP is a simple yet powerful language designed for creating HTML
content. This chapter covers essential background on the PHP
language. It describes the nature and history of PHP; which platforms
it runs on; and how to download, install, and configure it. This
chapter ends by showing you PHP in action, with a quick walkthrough
of several PHP programs that illustrate common tasks, such as
processing form data, interacting with a database, and creating
graphics.
1.1. What Does PHP Do?
PHP can be used in three primary ways:
- Server-side scripting
-
PHP was originally designed to create dynamic web content, and it is
still best suited for that task. To generate HTML, you need the PHP
parser and a web server to send the documents. Lately, PHP has also
become popular for generating XML documents, graphics, Flash
animations, PDF files, and more.
- Command-line scripting
-
PHP can run scripts from the command line, much like Perl, awk, or
the Unix shell. You might use the command-line scripts for system
administration tasks, such as backup and log parsing.
-
Client-side GUI applications
-
Using PHP-GTK (http://gtk.php.net), you can write
full-blown, cross-platform GUI applications in PHP.
In this book, we'll concentrate on the first item,
using PHP to develop dynamic web content.
PHP runs on all major
operating systems, from Unix variants
including Linux, FreeBSD, and Solaris to such diverse platforms as
Windows and Mac OS X. It can be used with all leading web servers,
including Apache, Microsoft IIS, and the Netscape/iPlanet servers.
The language is very flexible. For example, you
aren't limited to outputting just HTML or other text
files—any document format can be generated. PHP has built-in
support for generating PDF files, GIF, JPG, and PNG images, and Flash
movies.
One of PHP's most significant features is its
wide-ranging support for
databases. PHP
supports all major databases (including MySQL, PostgreSQL, Oracle,
Sybase, and ODBC-compliant databases), and even many obscure ones.
With PHP, creating web pages with dynamic content from a database is
remarkably simple.
Finally, PHP provides a library of PHP code to perform common tasks,
such as database abstraction, error handling, and so on, with the
PHP Extension and Application
Repository (PEAR). PEAR is a framework and distribution system for
reusable PHP components. You can find out more about it at
http://pear.php.net.
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