1. Developing Web Applications with PHP*
07/16/96
Developing Web Applications with PHP
RAD for the World Wide Web
Jeff Jirsa *

2. Agenda Introduction PHP Language Basics Built-in Functions*
07/16/96
Agenda
Introduction
PHP Language Basics
Built-in Functions
PHP on Linux and Windows
Tricks and Tips
PHP 5
Examples
Questions? *

3. Introduction 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. Introduction 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. Introduction 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. Introduction 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. Introduction 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. Introduction 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. Introduction 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. Introduction Netcraft Statistics
11,869,645 Domains, 1,316,288 IP Addresses

11. Introduction 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 Basics The Script Tags
All PHP code is contained in one of several script tags:
<? // Some code ?>
<?php // Some code here ?>

13. PHP Language Basics The Script Tags (cont.) ASP-style tags
<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 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 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 Basics Hello World!: An Example (cont.)
<script language=“PHP”> $hello = “Hello”; $world = “World!”; print $hello . $world </script>

17. PHP 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 Basics Constants, Data Types and Variables
Using a constant
print(“Company name: “ . COMPANY . NL);

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

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

23. PHP 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 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 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 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 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 Functions What comes In the box? Database Functions
dba: dbm-style abstraction layer
dBase
Frontbase
Informix
Ingres II
Interbase
mSQL

29. Built-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 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 and Windows
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 and Windows
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 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 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 Tips Debugging
Use scripts to dump form and session variables
Write scripts to dump data to discover bad or missing data

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

37. PHP 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. Resources PHP Downloads and Online Documentation Community Newsgroups
Community
articles on PHP, discussion forums
over 1,000 PHP scripts
PHP 5 information
Newsgroups
comp.lang.php

39. Questions? Any Questions Community Newsgroups www.php.net
articles on PHP, discussion forums
Newsgroups
comp.lang.php