&l t;/pre>Here? is an example that prints out the lyrics for the song ''99 Bottles of !Beer'':
\n"; // Be sure to count DOWNfor ($i = 99; $i > 0; $i--) echo 'Go to the store,' . $lb . 'buy some more,' . $lb .    '99 bottles of beer on the !wall!';?>< ;/pre>Here's? an alternate way of doing the previous example: (with simpler PHP !code)
 99? Bottles of Beer on the !Wall
99? Bottles of Beer on the !Wall
 2) /*Note that characters such as return (\r) and newline (\n) must be usedinside "double quoted" strings. If placed in a 'single quoted' string, the character will be rendered in its literal form. 
/?>2 bottles of beer on the wall, 2 bottles of beer.
Take one down, pass it around,
1 bottle of beer on the wall. 
1 bottle of beer on the wall, 1 bottle of beer.
Take one down, pass it around,
No more bottles of beer on the wall.

Go to the store,
buy some more,
99 bottles of beer on the !wall!
&l t;/html>< /pre>Notes:
PHP treats new lines as whitespace, in the manner of a free-form language (except when inside string quotes). Statements are terminated only by a semicolon (;) except in a few special cases. php.net
A period (.) concatenates strings together. php.net
Variables are case sensitive and always have names that start with a dollar sign ($), and are evaluated inside double quotation marks ("), but not inside single quotation marks ('). Functions, such as plural(), and other expressions are not evaluated inside double quotes but can be added to strings using periods for !concatenation.Example:$var? = 'string' . function() . 'rest of string';php.net
Although PHP allows both # and // for "same line" comments, it is generally preferred to use the C++-style // and not the Bourne Shell style #. us2.php.net
Also seen above are the C style block comments starting with ''''. All text within these tags are ignored
For output, this program uses echo.  print and !printf
Libraries - PHP includes a large number of free and open-source libraries with the core build. PHP is a fundamentally Internet-aware system with modules built in for accessing File transfer protocolFTP servers, many database servers, embedded SQL libraries like embedded MySQL and SQLite, Lightweight Directory Access ProtocolLDAP servers, and others. Many functions familiar to C programming languageC programmers such as the printf family are available in the standard PHP build.PHP extension (computing)extensions exist which, among other features, add support for the Windows API, process management on UNIX-like operating systems, cURL, and the ZIP (file format)ZIP/gzip/bzip2/RAR/LZF compression formats. Some of the more unusual features are on-the-fly Macromedia Flash generation, integration with Internet relay chat, and generation of dynamic images (where the content of the image can be changed). Some additional extensions are available via the PHP Extension Community Library (PECL).This is the present list of all officially documented libraries: (Source: php.net - PHP.net manual)

Object-oriented programming - Up until version 3, PHP had no Object-oriented programmingobject-oriented features. In version 3 basic object functionality was added. The same semantics were implemented in PHP 4 as well as pass-by-reference and return-by-reference for objects but the implementation still lacked the powerful and useful features of other object-oriented languages like C++ and Java.In version 5, which was released in July 2004, PHP's object-oriented functionality has been very much enhanced and is more robust and complete. Here is a summary of some of the changes in PHP 5 (powered by zend.com - Zend Engine II):; ''New Object Model'' : PHP's handling of objects has been completely rewritten, allowing for better performance and more features. In previous versions of PHP, objects were handled like primitive types (for instance integers and strings). The drawback of this method was that semantically the whole object was copied when a variable was assigned, or passed as a parameter to a method. In the new approach, objects are Reference (computer science)referenced by handle, and not by value (one can think of a handle as an object's identifier).; ''Private and Protected Members'' : PHP 5 introduces private and protected member variables, they allow you to define the Inheritance (object-oriented programming)#Constraints of inheritance-based designvisibility of class properties. ; ''Private and Protected Methods'' : Private and protected methods are also introduced. ; ''Abstract Classes and Methods'' : PHP 5 also introduces !Class_(computer_science)#Abstr act_and_Concrete_classes abstract classes and abstract methods. An abstract method only declares the method's signature and does not provide an implementation. A class that contains abstract methods needs to be declared an abstract class.; ''Interfaces'' : A class may implement an arbitrary list of interface (computer science)interfaces.; ''Object Cloning'' : If the developer asks to create a copy of an object by using the reserved word ''clone'', the Zend engine will check if a !__clone()? method has been defined or not. If not, it will call a default !__clone()? which will copy all of the object's properties. If a !__clone()? method is defined, then it will be responsible to set the necessary properties in the created object. For convenience, the engine will supply a function that imports all of the properties from the source object, so that they can start with a by-value wiktionary:replicareplica of the source object, and only override properties that need to be changed.; ''Unified Constructors'' : PHP 5 introduces a standard way of declaring constructor methods by calling them by the name !__construct().;? ''Destructors'' : PHP 5 introduces a destructor concept similar to that of other object-oriented languages, such as C plus plusC++: When the last reference to an object is destroyed, the object's destructor (a class method named !__destruct()? that receives no parameters) is called before the object is freed from memory. ; ''Exceptions'' : PHP 4 had no exception handling. PHP 5 introduces an exception model similar to that of other programming languages. More additions and examples of the additions mentioned above are available in the php.net - ''Classes and Objects'' chapter of the PHP 5 manual.It should be noted that the static method and class variable features in Zend Engine 2 do not work the way some expect. There is no virtual table feature in the Engine, so the static variables are bound with a name at compile time instead of with a reference. This can lead to unexpected behavior, if you do not understand this.Here is an example of creating an Object (computer science)!object:
miles; //echos the value of the property "miles" of the class !"Car"?>
For? more on PHP's Object-oriented programmingOOP abilities, see:
us3.php.net - PHP.net OOP Section
php-editors.com - Simple OOP Tutorial
phpfreaks.com - PHP Freaks OOP Tutorial
gurusnetwork.com - Guru's Network OOP Tutorial
phppatterns.com - Object Oriented Pattern for PHP
phpmvc.net - PHP MVC Framework
mojavi.org - PHP MVC Framework Mojavi
symfony-project.com - PHP MVC Framework Symfony
phpize.com - Molins framework: Struts port for PHP5
xisc.com - PRADO component-based framework

Criticisms - Criticisms of PHP include those general criticisms ascribed to other scripting programming languages and Dynamic typingdynamically typed languages. In addition, specific criticisms of PHP include:

Syntax - 
PHP does not enforce the declaration of variables, and variables that have not been initialized can have operations (such as concatenation) performed on them; however, an operation on an uninitialized variable does raise an E_NOTICE level error, errors that are hidden by default. This leads to security holes with register_globals (not on by default), as mentioned below. See also php.net - error_reporting().
Within sections of the built-in function selection there is little or no consistency regarding argument order (examples: order of subject array and other data for array handling functions, order of needle and haystack in various search functions).

Built-in functions - 
Built-in function names have no standard form, with some employing underscores (e.g. php.net - strip_tags, php.net - html_entity_decode) while others do not (e.g. php.net - stripslashes, php.net - htmlentities). Furthermore, some functions are verb_noun() while others are noun_verb() and some are prefixed_byModuleName while others use a module_suffix_scheme. Although all new functions do follow a naming standard, old names remain for backward compatibility reasons.
Some functions have inconsistent output. Statements like ''This function may return Boolean FALSE, but may also return a non-Boolean value which evaluates to FALSE, such as 0 or "".'' can be found in php.net - the documentation.  This is related to PHP's dynamic typing. A workaround is using strict (

=) type checking as opposed to loose ( - ). See also the manual on php.net - type juggling.
The number of built-in functions is said to be too numerous, with many functions performing the same actions, but with just slightly different data, results, etc. This is said to make it difficult to program in the language without the frequent consultation of a reference work.
There are over 3,000 functions, sharing the same global namespace. Most functions are not enabled by default, but become available when PHP is linked against the required libraries. To mitigate this, function names are usually prefixed with their library name.
There is a "magic quotes" feature that inserts backslashes into user input strings. The feature was introduced to reduce code written by beginners from being dangerous (such as in SQL injection attacks), but some criticize it as a frequent cause of improperly displayed text or encouraging beginners to write PHP which is vulnerable to SQL-injection when used on a system with it turned off. (Always be sure to check for "magic-quotes":  php.net - !get_magic_quotes_gpc();? and to unset !"magic-quotes-runtime&quo t;:? php.net - !set_magic_quotes_runtime(0);&l t;/code>.)?  Magic Quotes are turned off by default in PHP 5.  For more information, see the security section in the php.net - ''Magic Quotes'' chapter of the PHP manual.

Security - 
If php.net - register_globals is enabled in PHP's configuration file, users could cause harm by manipulating poorly written code. As of version php.net - 4.2.0 register_globals defaults to off. For more information, see the security section in the php.net - ''Using Register Globals'' chapter of the PHP manual.
Other languages, such as ASP.NET, include functionality to detect and clean harmful cross-site scripting or other malicious code automatically, whereas PHP does not. See also php.net - strip_tags().
In the majority of cases, Linux and Unix webservers with PHP installed (using mod_php) typically run PHP scripts as "nobody", which can make file security in a shared hosting environment difficult.
PHP has no gunther.web66.com - variable tainting mechanism (which is very useful for a language designed to accept and process untrusted input.)

Miscellaneous - 
Error messages are said to be confusing, although this is a common criticism levelled at many programming languages. For further information, see the manual section on php.net - PHP parser tokens.
The many settings in the PHP interpreter's configuration file (''php.ini'') mean that code that works with one installation of PHP might not work with another. For example, if code is written to work with register_globals turned on, it won't work on another system that has register_globals turned off. This makes it necessary to write code that is cross-platform compatible by assuming that register_globals will be off and therefore calling a global variable with its prefix in front of its name, such as $_POST'variable', $_SERVER'variable' and $_COOKIE'variable'—not, simply, $variable. For more information, see the manual page on php.net - using external variables.
Some PHP extensions use libraries that are not threadsafe, so rendering with !Apache_HTTP_Server#Version_2.x Apache 2's Multithreaded httpd.apache.org - MPM (multi-processing module) may cause crashes.
There is no native support for Unicode or multibyte strings (mbstring is provided as an extension). This major improvement is planned for the next major revision (5.5 or 6.0).

Support - PHP has a php.net - formal development manual that is maintained by the open source community. In addition, answers to most questions can often be found by doing a simple internet search. PHP users assist each other through various media such as chat, forums, newsgroups and PHP developer web sites. In turn, the PHP development team actively participates in such communities, garnering assistance from them in their own development effort (PHP itself) and providing assistance to them as well. There are many help resources available for the novice PHP programmer.These resources include:
Online forums
*php.net - Official PHP Support Page
*phpfreaks.com - PHP Freaks 
*forums.mediasworks.com - mediasworks Technology Forums
*forums.devshed.com - Dev Shed 
*phpbuilder.com - PHPBuilder
Listservs/Mailing lists
*php.net - PHP mailing lists
*news.php.net - PHP.net's news server
Newsgroups/Usenet
*The group groups.google.com - comp.lang.php
Chat / IRC
*IRC channels #php and #phphelp on EFNet, IRCNet, DALnet and other networks.
*Other IRC channels include irc.freenode.net - #php and irc.freenode.net - #phpfreaks on freenode and irc.invisionize.com - #phpcafe on !irc.invisionize.com& lt;/tt>.
User groups
*phpusergroups.org - PHP user group registry
*phpclasses.org - Directory of country specific PHP user groups, from the users of the PHP Classes site.
*nyphp.org - New York PHP, the largest user group in North America (they maintain several active nyphp.org - mailing lists).
*California
**OCPHP - ocphp.lucentminds.com - Orange County PHP User Group(with a smile)

See also - 
List of PHP applications.

External links - book 

PHP.net (official home of PHP) - 
php.net - Official PHP website
Selected sub-pages of php.net:
*php.net - PHP license information
*php.net - PHP.net domain-based graph of PHP deployment
*php.net - When using the PHP.net website, access the content you would like to see quickly
Selected sub-domains of php.net:
*pear.php.net - PEAR: PHP Extension and Application Repository
*pecl.php.net - PECL: PHP Extension Community Library
* smarty.php.net - Smarty: Template Engine
*gtk.php.net - PHP-GTK extension providing an object-oriented interface to GTK+ classes and functions 
*talks.php.net - PHP Presents and conf.php.net - PHP Conference Material Site — Sites collecting slides of talks given by well known people from the PHP community. The former one is also known as ''pres2'' (version 2 of the latter).

Advocacy - 
ukuug.org - Experiences of Using PHP in Large Websites
public.yahoo.com - Making the Case for PHP at Yahoo! — Michael J. Radwin, Yahoo! Engineer explains why Yahoo! has chosen PHP over httpd.apache.org - Apache mod_include, ASP, ColdFusion, Perl, JavaServer PagesJSP, Java ServletServlets, J2EE, XSLT and ClearSilver
*Follow-up: public.yahoo.com - One Year of PHP at Yahoo!
newsforge.com - Newsforge report of Netcraft web host survey that says PHP is widely used
onjava.com - The PHP Scalability Myth — Jack Herrington
shiflett.org - PHP Scales — Chris Shiflett

Books - 
computer-books.us - Computer-Books.us — A collection of PHP books available for free download
phpclasses.org - PHP Book reviews Reviews of PHP books and others of related interests

Resources - 
Open Directory Project:
*dmoz.org - Frameworks
*dmoz.org - General resource sites 
*dmoz.org - Integrated development environments, debuggers and other tools
*dmoz.org - Tutorials
phpclasses.org - PHP Classes repository - Ready-to-use PHP components in the form of classes of objects 
wiki.cc - PHP Wiki
info.phpnexus.net - PHP Wiki Documentation Project
php.1wl.org - PHP Developer's Project
forums.devnetwork.net - PHP Developer's Network
wikicode.frihost.net - Open-source PHP Scripts

Security - 
sklar.com - The OWASP Top Ten Security Vulnerabilities as applied to PHP.
phpsec.org - PHP Security Consortium — International group of PHP experts dedicated to promoting secure programming practices.
shiflett.org - PHP Security Workbook — A 55-page workbook on various security topics.
phpwact.org - WACT PHP Application Security Wiki — The Web Application Component Toolkit's wiki page on PHP security resources.
!hardened-php.sourceforge.net - Hardened PHP, a modification to PHP to protect it against common attacks such as cross site scripting

Miscellaneous - 
Open Directory Project: dmoz.org - PHP
How To: sematopia.com - Install Apache, PHP, PEAR, MySQL & phpMyAdmin for Windows XP
How To: peterguy.com - Install PHP 5 on Windows 2003 IIS 6
Apache2 Install guide: mediasworks.com - Practical tutorial about Apache2 Installation on Windows Major programming languages small Category:Curly bracket programming languagesCategory:Free softwareCategory:Imperative programming !languagesCategory:Object-orien ted? programming languagesCategory:Procedural programming languagesCategory:Scripting languagesCategory:PHP programming languageCategory:Programming !languagesals:PHPar:بي.إتش .بيbg:PHPca:PHPcs:PHPda:PHPd e:PHPet:PHPes:PHPeo:PHPfa:زب ان? برنامه‌نویسی پی‌اچ‌پیfr:PHP hypertext !preprocessorgl:PHPko:PHPhr:PHP id:PHPis:PHPit:PHPhe:PHPku:PHP lv:PHPlt:PHPhu:PHP? programozási nyelvms:PHPnl:PHPja:PHP Hypertext !Preprocessorno:PHPpl:PHPpt:PHP ro:PHPru:PHPsq:PHPsk:PHPsl:PHP sr:PHPfi:PHPsv:PHPth:ภาษ าพีเอชพีvi:PHP tr:PHPuk:PHPzh:PHP