This document provides an overview of PHP and its history and capabilities. It begins with a brief history of PHP, describing how it was created in 1995 and evolved through several versions. It then covers PHP language basics like script tags, data types, variables, and built-in functions. The document also discusses considerations for coding PHP applications to be portable across Linux and Windows and provides tips for debugging and development tools. Finally, it outlines some new features being introduced in PHP 5 like complete object support.

1. Developing WebDeveloping Web
Applications with PHPApplications with PHP
RAD for the World
Wide Web
Jeff Jirsa
jjirsa@xnet.com

2. AgendaAgenda
– Introduction
– PHP Language Basics
– Built-in Functions
– PHP on Linux and Windows
– Tricks and Tips
– PHP 5
– Examples
– Questions?

3. IntroductionIntroduction
• What is PHP?
– PHP stands for "PHP Hypertext
Preprocessor”
– An embedded scripting language for HTML
like ASP or JSP
– A language that combines elements of
Perl, C, and Java

4. IntroductionIntroduction
• History of PHP
– Created by Rasmus Lerdorf in 1995 for
tracking access to his resume
– Originally a set of Perl scripts known as the
“Personal Home Page” tools
– Rewritten in C with database functionality
– Added a forms interpreter and released as
PHP/FI: includes Perl-like variables, and
HTML embedded syntax

5. IntroductionIntroduction
• History of PHP (cont.)
– Rewritten again in and released as version
2.0 in November of 1997
– Estimated user base in 1997 is several
thousand users and 50,000 web sites
served
– Rewritten again in late 1997 by Andi
Gutmans and Zeev Suraski
– More functionality added, database
support, protocols and APIs

6. IntroductionIntroduction
• History of PHP (cont.)
– User base in 1998 estimated 10,000 users
and 100,000 web sites installed
– Version 3.0 was released in June 1998 as
PHP
– Estimated user base in tens of thousands
and hundreds of thousands of web sites
served

7. IntroductionIntroduction
• History of PHP (cont.)
– Rewritten again in 1997 by Andi Gutmans
and Zeev Suraski
– More functionality added (OOP features),
database support, protocols and APIs
– PHP 3.0 is released in June 1998 with
some OO capability
– The core is rewritten in 1998 for improved
performance of complex applications

8. IntroductionIntroduction
• History of PHP (cont.)
– The core is rewritten in 1998 by Zeev and
Andi and dubbed the “Zend Engine”
– The engine is introduced in mid 1999 and
is released with version 4.0 in May of 2000
– The estimated user base is hundreds of
thousands of developers and several
million of web sites served

9. IntroductionIntroduction
• History of PHP (cont.)
– Version 5.0 will include version 2.0 of the
Zend Engine
• New object model is more powerful and
intuitive
• Objects will no longer be passed by value; they
now will be passed by reference
• Increases performance and makes OOP more
attractive

10. IntroductionIntroduction
• Netcraft Statistics
– 11,869,645 Domains, 1,316,288 IP Addresses

11. IntroductionIntroduction
• Performance*
– Zdnet Statistics
• PHP pumped out about 47 pages/second
• Microsoft ASP pumped out about 43
pages/second
• Allaire ColdFusion pumped out about 29
pages/second
• Sun Java JSP pumped out about 13
pages/second
* From PHP HOWTO, July 2001

12. PHP Language BasicsPHP Language Basics
• The Script Tags
– All PHP code is contained in one of several
script tags:
• <?
// Some code
?>
• <?php
// Some code here
?>

13. PHP Language BasicsPHP Language Basics
• The Script Tags (cont.)
• <script language=“PHP">
// Some code here
</script>
– ASP-style tags
• Introduced in 3.0; may be removed in the future
• <%
// Some code here
%>

14. PHP Language BasicsPHP Language Basics
• The Script Tags (cont.)
– “Echo” Tags
– <table>
<tr>
<td>Name:</td><td><?= $name ?></td>
</tr>
<tr>
<td>Address:</td><td><?= $address ?></td>
</tr>
</table>

15. PHP Language BasicsPHP Language Basics
• Hello World!: An Example
– Like Perl, there is more than one way to do
it
• <?php echo “Hello World!”; ?>
• <?php
$greeting = “Hello World!”
printf(“%s”, $greeting);
php?>

16. PHP Language BasicsPHP Language Basics
• Hello World!: An Example (cont.)
• <script language=“PHP”>
$hello = “Hello”;
$world = “World!”;
print $hello . $world
</script>

17. PHP Language BasicsPHP Language Basics
• Constants, Data Types and
Variables
– Constants define a string or numeric value
– Constants do not begin with a dollar sign
– Examples:
• define(“COMPANY”, “Acme Enterprises”);
• define(“YELLOW”, “#FFFF00”);
• define(“PI”, 3.14);
• define(“NL”, “<br>n”);

18. PHP Language BasicsPHP Language Basics
• Constants, Data Types and
Variables
– Using a constant
• print(“Company name: “ . COMPANY . NL);

19. PHP Language BasicsPHP Language Basics
• Constants, Data Types and
Variables
– Data types
• Integers, doubles and strings
– isValid = true; // Boolean
– 25 // Integer
– 3.14 // Double
– ‘Four’ // String
– “Total value” // Another string

20. PHP Language BasicsPHP Language Basics
• Constants, Data Types and
Variables
– Data types
• Strings and type conversion
– $street = 123;
– $street = $street . “ Main Street”;
– $city = ‘Naperville’;
$state = ‘IL’;
– $address = $street;
– $address = $address . NL . “$city, $state”;
– $number = $address + 1; // $number equals
124

21. PHP Language BasicsPHP Language Basics
• Constants, Data Types and
Variables
– Data types
• Arrays
– Perl-like syntax
• $arr = array("foo" => "bar", 12 => true);
– same as
• $arr[“foo”] = “bar”;
• $arr[12] = true;

22. PHP Language BasicsPHP Language Basics
• Constants, Data Types and
Variables
• Arrays (cont.)
– <?php
$arr = array("somearray" => array(6 => 5, 13 => 9,
"a" => 42));
echo $arr["somearray"][6]; // 5
echo $arr["somearray"][13]; // 9
echo $arr["somearray"]["a"]; // 42
?>

23. PHP Language BasicsPHP Language Basics
• Constants, Data Types and
Variables
– Objects
– Currently not much more advanced than than
associative arrays Using constants
– Before version 5.0, objects are passed by value
• Slow
• Functions can not easily change object variables

24. PHP Language BasicsPHP Language Basics
• Constants, Data Types and
Variables
– Operators
– Contains all of the operators like in C and Perl (even
the ternary)
– Statements
– if, if/elseif
– Switch/case
– for, while, and do/while loops
– Include and require statements for code reuse

25. Built-in FunctionsBuilt-in Functions
• What comes In the box?
– Array Manipulator Functions
• sort, merge, push, pop, slice, splice, keys,
count
– CCVS: Interface to Red Hat’s credit system
– COM functions: Interface to Windows COM
objects
– Date and Time Functions
• getdate, mkdate, date, gettimeofday, localtime,
strtotime, time

26. Built-in FunctionsBuilt-in Functions
• What comes In the box?
– Directory Functions
• Platform independent
– Error Handling Functions
• Recover from warnings and errors
– Filesystem Functions
• Access flat files
• Check directory, link, and file status information
• Copy, delete, and rename files

27. Built-in FunctionsBuilt-in Functions
• What comes In the box?
– IMAP Functions
• Manipulate mail boxes via the IMAP protocol
– LDAP Functions
• Works with most LDAP servers
– Mail Functions
• mail($recipient, $subject, $message)

28. Built-in FunctionsBuilt-in Functions
• What comes In the box?
– Database Functions
• dba: dbm-style abstraction layer
• dBase
• Frontbase
• Informix
• Ingres II
• Interbase
• mSQL

29. Built-in FunctionsBuilt-in Functions
• What comes In the box?
– Database Functions (cont.)
• MySQL
• Oracle
• PostgreSQL
• SQL Server
– MING
• Macromedia Flash
– PDF
• Create/manipulate PDF files dynamically

30. Built-in FunctionsBuilt-in Functions
• What comes In the box?
– POSIX Functions
• Manipulate process information
– Regular Expression Functions
• Uses POSIX regex
– Semaphore and Socket Functions
• Available only on Unix
– Session Management Functions

31. PHP on Linux andPHP on Linux and
WindowsWindows
• Code Portability
– The obvious: don’t use Unix or Windows
specific functions
– Create a reusable module for file system
differences, for example:
– if( PHP_OS == "Linux" )
{
$ConfigPath = "/var/www/conf";
$DataPath = "/var/www/data";
}

32. PHP on Linux andPHP on Linux and
WindowsWindows
• Code Portability
– if( ereg("WIN", PHP_OS) )
{
$ApachePath = “C:/Program Files/Apache
Group/Apache”;
$ConfigPath = ”$ApachePath/htdocs/conf";
$DataPath = "$ApachePath/htdocs/data";
}
$ConfigFile = "$ConfigPath/paperwork.conf";
$CountryList = "$DataPath/countries.txt";
$StateAbbrList = "$DataPath/usstateabbrs.txt";
$StateNameList = "$DataPath/usstatenames.txt";

33. Tricks and TipsTricks and Tips
• Coding
– Prototype your web pages first
• Separate the design of the site from the coding
– Turn repetitive code into functions
• Makes for more maintainable and reusable
code
– Turn grunt code into functions
• Database access, configuration file access

34. Tricks and TipsTricks and Tips
• Debugging
– Feature: PHP is not a strongly typed
language
• Variables can be created anywhere in your
code
– Undocumented Feature: PHP is not a
strongly typed language
• Typos in variable names will cause stuff to
happen

35. Tricks and TipsTricks and Tips
• Debugging
– Use scripts to dump form and session
variables
• Write scripts to dump data to discover bad or
missing data

36. Tricks and TipsTricks and Tips
• Development Tools
– Color coding editors
• vim, Emacs, Visual SlickEdit
– IDEs
• Windows
– Macromedia Dreamweaver
– Allaire Homesite
– Zend’s PHPEdit
• Linux
– ???

37. PHP 5PHP 5
• Release Date
– ???
• Features
– Complete objects
• Objects with constructors
• Abstract classes
• Private, protected and abstract functions
• Private, protected and constant variables
• Namespaces
• Exception handling with try/catch blocks

38. ResourcesResources
• PHP Downloads and Online
Documentation
– www.php.net
• Community
– www.phpbuilder.com: articles on PHP, discussion
forums
– www.phpresourceindex.com: over 1,000 PHP scripts
– www.phpvolcano.com: PHP 5 information
• Newsgroups
– comp.lang.php

39. Questions?Questions?
– Any Questions
• www.php.net
– Community
• www.phpbuilder.com: articles on PHP,
discussion forums
– Newsgroups
• comp.lang.php