Chapter 1 An Introduction to PHP The past five years have been fantastic in terms of the explosive growth of the Internet and the
new ways in which people are able to communicate with one another. Spearheading this
phenomenon has been the World Wide Web (WWW), with thousands of new sites being
launched daily and consumers being consistently offered numerous outstanding services via this
new communications medium. With this exploding market has come a great need for new
technologies and developers to learn these technologies. Chances are that if you are reading
this paragraph, you are one of these Web developers or are soon to become one. Regardless of
your profession, you’ve picked this book up because you’ve heard of the great new technology
called PHP.
This chapter introduces the PHP language, discusses its history and capabilities, and provides
the basic information you need to begin developing PHPenabled sites. Several examples are
provided throughout, hopefully serving to excite you about what PHP can offer you and your
organization. You will learn how to install and configure the PHP software on both Linux/UNIX
and Windows machines, and you will learn how to embed PHP in HTML. At the conclusion of
the chapter, you will be ready to begin delving into the many important aspects of the PHP
language. So light the fire, turn on your favorite jazz album, and curl up on the lazyboy; you
are about to learn what will be one of the most exciting additions to your resume: PHP
programming.
An Abbreviated History PHP set its roots in 1995, when an independent software development contractor named
Rasmus Lerdorf developed a Perl/CGI script that enabled him to know how many visitors were
reading his online resume. His script performed two duties: logging visitor information and
displaying the count of visitors to the Web page. Because the WWW as we know it today was
still so young at that time, tools such as these were nonexistent, and they prompted emails
inquiring about Lerdorf’s scripts. Lerdorf thus began giving away his toolset, dubbed Personal
Home Page (PHP), or Hypertext Preprocessor.
The clamor for the PHP toolset prompted Lerdorf to begin developing additions to PHP, one of
which converted data entered in an HTML form into symbolic variables that allowed for their
export to other systems. To accomplish this, he opted to continue development in C code rather
than Perl. This addition to the existing PHP toolset resulted in PHP 2.0, or PHP-FI (Personal
Home Page—Form Interpreter). This 2.0 release was accompanied by a number of
enhancements and improvements from programmers worldwide.
The new PHP release was extremely popular, and a core team of developers soon formed. They
kept the original concept of incorporating code directly alongside HTML and rewrote the
parsing
engine, giving birth to PHP 3.0. By the 1997 release of version 3.0, over 50,000 users were
using PHP to enhance their Web pages. Development continued at a hectic pace over the next
two years, with hundreds of functions being added and the user count growing in leaps and
bounds. At the onset of 1999, Netcraft (http://www.netcraft.com) reported a conservative
estimate of a user base surpassing 1,000,000, making PHP one of the most popular scripting
languages in the world.
Early 1999 saw the announcement of the upcoming PHP 4.0. Although one of PHP’s strongest
features was its proficiency at executing scripts, the developers had not intended that large-scale
applications were going to be built using PHP. Thus they set out to build an even-more robust
parsing engine, better known as Zend (http://www.zend.com). Development continued rapidly,
culminating in the May 22, 2000, release of PHP 4.0.
In addition to the Zend processor, Zend technologies, based in Israel, offers the Zend optimizer,
which increases even further the performance benefits of the Zend parsing engine. Available
for download free of charge, the benchmarks have shown that the optimizer can result in a 40
to 100 percent overall performance gain. Check out the Zend site for more information.
At the time of this writing, according to Netcraft (http://www.netcraft.com), PHP is installed on
over 3.6 million domains, making it one of the most popular scripting languages in the world.
The future of PHP indeed looks bright, as major Web sites and personal users alike continue to
embrace the product.
A Programmer's Introduction to PHP 4.0
