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Usual file extensions .php, .phtml .php5 .phps
Paradigm imperative, object-oriented
Appeared in 1995[1]
Designed by Rasmus Lerdorf
Developer The PHP Group
Stable release 5.2.13 / 5.3.2 (5.2.13 February 25, 2010; 22 day(s) ago (2010-02-25) / 5.3.2: March 4, 2010; 15 day(s) ago (2010-03-04))
Preview release 6.0.0-dev[2]
Typing discipline Dynamic, weak
Major implementations Zend Engine, Roadsend PHP, Phalanger, Quercus, Project Zero, HipHop
Influenced by C, Perl, Java, C++, Tcl[1]
Influenced PHP4Delphi
Programming language C
OS Cross-platform
License PHP License

PHP: Hypertext Preprocessor (the name is a recursive acronym) is a widely used, general-purpose scripting language that was originally designed for web development to produce dynamic web pages. For this purpose, PHP code is embedded into the HTML source document and interpreted by a web server with a PHP processor module, which generates the web page document. As a general-purpose programming language, PHP code is processed by an interpreter application in command-line mode performing desired operating system operations and producing program output on its standard output channel. It may also function as a graphical application. PHP is available as a processor for most modern web servers and as standalone interpreter on most operating systems and computing platforms.

PHP was originally created by Rasmus Lerdorf in 1995[1] and has been in continuous development ever since. The main implementation of PHP is now produced by The PHP Group and serves as the de facto standard for PHP as there is no formal specification.[3] PHP is free software released under the PHP License, which is incompatible with the GNU General Public License (GPL) because restrictions exist regarding the use of the term PHP.[4]



Rasmus Lerdorf, who wrote the original Common Gateway Interface component, Andi Gutmans and Zeev Suraski, who rewrote the parser that formed PHP 3

PHP originally stood for personal home page.[3] It began in 1994 as a set of Common Gateway Interface (CGI) binaries written in the C programming language by the Danish/Greenlandic programmer Rasmus Lerdorf.[5][6] Lerdorf initially created these Personal Home Page Tools to replace a small set of Perl scripts he had been using to maintain his personal homepage. The tools were used to perform tasks such as displaying his résumé and recording how much traffic his page was receiving.[3]

He combined these binaries with his Form Interpreter to create PHP/FI, which had more functionality. PHP/FI included a larger implementation for the C programming language and could communicate with databases, enabling the building of simple, dynamic web applications. Lerdorf released PHP publicly on June 8, 1995, to accelerate bug location and improve the code.[7] This release was named PHP version 2 and already had the basic functionality that PHP has today. This included Perl-like variables, form handling, and the ability to embed HTML. The syntax was similar to Perl but was more limited, simpler, and less consistent.[3]

Zeev Suraski and Andi Gutmans, two Israeli developers at the Technion IIT, rewrote the parser in 1997 and formed the base of PHP 3, changing the language's name to the recursive initialism PHP: Hypertext Preprocessor.[3] The development team officially released PHP/FI 2 in November 1997 after months of beta testing. Afterwards, public testing of PHP 3 began, and the official launch came in June 1998. Suraski and Gutmans then started a new rewrite of PHP's core, producing the Zend Engine in 1999.[8] They also founded Zend Technologies in Ramat Gan, Israel.[3]

On May 22, 2000, PHP 4, powered by the Zend Engine 1.0, was released.[3] As of August 2008 this branch is up to version 4.4.9. PHP 4 is no longer under development nor will any security updates be released.[9][10]

On July 13, 2004, PHP 5 was released, powered by the new Zend Engine II.[3] PHP 5 included new features such as improved support for object-oriented programming, the PHP Data Objects extension (which defines a lightweight and consistent interface for accessing databases), and numerous performance enhancements.[11] In 2008 PHP 5 became the only stable version under development. Late static binding has been missing from PHP and has been added in version 5.3.[12][13]

PHP 6 is under development alongside PHP 5. Major changes include the removal of register_globals,[14] magic quotes, and safe mode.[9][15] The reason for the removals was that register_globals had given way to security holes, and magic quotes had an unpredictable nature, and was best avoided. Instead, to escape characters, magic quotes may be substituted with the addslashes() function, or more appropriately an escape mechanism specific to the database vendor itself like mysql_real_escape_string() for MySQL. Functions that will be removed in PHP 6 have been deprecated in PHP 5.3 and will produce a warning if used.[16]

Many high-profile open-source projects ceased to support PHP 4 in new code as of February 5, 2008, because of the GoPHP5 initiative [17], provided by a consortium of PHP developers promoting the transition from PHP 4 to PHP 5.[18][19]

PHP currently does not have native support for Unicode or multibyte strings; Unicode support will be included in PHP 6 and will allow strings as well as class, method, and function names to contain non-ASCII characters.[20][21]

PHP interpreters are available on both 32-bit and 64-bit operating systems, but on Microsoft Windows the only official distribution is a 32-bit implementation, requiring Windows 32-bit compatibility mode while using Internet Information Services (IIS) on a 64-bit Windows platform. As of PHP 5.3.0, experimental 64-bit versions are available for MS Windows.[22]

Release history

Red Release no longer supported
Green Release still supported
Blue Future release
Major version Minor version Release date Notes
1 1.0.0 1995-06-08 Officially called "Personal Home Page Tools (PHP Tools)". This is the first use of the name "PHP".[3]
2 2.0.0 1997-11-01 Considered by its creator as the "fastest and simplest tool" for creating dynamic web pages.[3]
3 3.0.0 1998-06-06 Development moves from one person to multiple developers. Zeev Suraski and Andi Gutmans rewrite the base for this version.[3]
4 4.0.0 2000-05-22 Added more advanced two-stage parse/execute tag-parsing system called the Zend engine.[23]
4.1.0 2001-12-10 Introduced 'superglobals' ($_GET, $_POST, $_SESSION, etc.)[23]
4.2.0 2002-04-22 Disabled register_globals by default. Data received over the network is not inserted directly into the global namespace anymore, closing possible security holes in applications.[23]
4.3.0 2002-12-27 Introduced the CLI, in addition to the CGI.[23][24]
4.4.0 2005-07-11 Added man pages for phpize and php-config scripts.[23]
4.4.8 2008-01-03 Several security enhancements and bug fixes. Was to be the end of life release for PHP 4. Security updates only until 2008-08-08, if necessary.[25]
4.4.9 2008-08-07 More security enhancements and bug fixes. The last release of the PHP 4.4 series.[26][27]
5 5.0.0 2004-07-13 Zend Engine II with a new object model.[28]
5.1.0 2005-11-24 Performance improvements with introduction of compiler variables in re-engineered PHP Engine.[28]
5.2.0 2006-11-02 Enabled the filter extension by default.[28]
5.2.11 2009-09-16 Bug and security fixes.
5.2.12 2009-12-17 Over 60 bug fixes, including 5 security fixes.
5.2.13 2010-02-25 Bug and security fixes.
5.3.0 2009-06-30 Namespace support; Late static bindings, Jump label (limited goto), Native closures, Native PHP archives (phar), garbage collection for circular references, improved Windows support, sqlite3, mysqlnd as a replacement for libmysql as underlying library for the extensions that work with MySQL, fileinfo as a replacement for mime_magic for better MIME support, the Internationalization extension, and deprecation of ereg extension.
5.3.1 2009-11-19 Over 100 bug fixes, some of which were security fixes as well.
5.3.2 2010-03-04 Includes a large number of bug fixes.
6 6.0.0 No date set Unicode support; removal of 'register_globals', 'magic_quotes' and 'safe_mode'; Alternative PHP Cache


PHP is a general-purpose scripting language that is especially suited to server-side web development where PHP generally runs on a web server. Any PHP code in a requested file is executed by the PHP runtime, usually to create dynamic web page content. It can also be used for command-line scripting and client-side GUI applications. PHP can be deployed on most web servers, many operating systems and platforms, and can be used with many relational database management systems. It is available free of charge, and the PHP Group provides the complete source code for users to build, customize and extend for their own use.[29]

PHP primarily acts as a filter,[30] taking input from a file or stream containing text and/or PHP instructions and outputs another stream of data; most commonly the output will be HTML. Since PHP 4, the PHP parser compiles input to produce bytecode for processing by the Zend Engine, giving improved performance over its interpreter predecessor.[31]

Originally designed to create dynamic web pages, PHP now focuses mainly on server-side scripting,[32] and it is similar to other server-side scripting languages that provide dynamic content from a web server to a client, such as Microsoft's Active Server Pages, Sun Microsystems' JavaServer Pages,[33] and mod_perl. PHP has also attracted the development of many frameworks that provide building blocks and a design structure to promote rapid application development (RAD). Some of these include CakePHP, Symfony, CodeIgniter, and Zend Framework, offering features similar to other web application frameworks.

The LAMP architecture has become popular in the web industry as a way of deploying web applications. PHP is commonly used as the P in this bundle alongside Linux, Apache and MySQL, although the P may also refer to Python or Perl or some combination of the three.

As of April 2007, over 20 million Internet domains had web services hosted on servers with PHP installed and mod_php was recorded as the most popular Apache HTTP Server module.[34] Significant websites are written in PHP including the user-facing portion of Facebook,[35] Wikipedia (MediaWiki),[36] Yahoo!,[citation needed] MyYearbook,[citation needed] Digg,[citation needed] Joomla, eZ_Publish, WordPress,[37] YouTube in its early stages,[citation needed] Drupal, Tagged[citation needed] and Moodle [38].


The National Vulnerability Database stores all vulnerabilities found in computer software. The overall proportion of PHP-related vulnerabilities on the database amounted to: 20% in 2004, 28% in 2005, 43% in 2006, 36% in 2007, 35% in 2008, and 30% in 2009.[39] Most of these PHP-related vulnerabilities can be exploited remotely: they allow crackers to steal or destroy data from data sources linked to the webserver (such as an SQL database), send spam or contribute to DoS attacks using malware, which itself can be installed on the vulnerable servers.

These vulnerabilities are caused mostly by not following best practice programming rules: technical security flaws of the language itself or of its core libraries are not frequent (23 in 2008, about 1% of the total). [40][41] Recognizing that programmers cannot be trusted, some languages include taint checking to detect automatically the lack of input validation which induces many issues. Such a feature is being developed for PHP,[42] but its inclusion in a release has been rejected several times in the past.[43][44]

Hosting PHP applications on a server requires a careful and constant attention to deal with these security risks.[45] There are advanced protection patches such as Suhosin and Hardening-Patch, especially designed for web hosting environments.[46]


        <title>PHP Test</title>
             echo "Hello World";
             /* echo("Hello World"); works as well.
                However, echo isn't a function (it's a language construct),
                so in some cases, such as when multiple parameters
                are passed to echo, parameters can not be
                enclosed in parentheses */

PHP code embedded within HTML

PHP only parses code within its delimiters. Anything outside its delimiters is sent directly to the output and is not processed by PHP, however, non-PHP text is still subject to control structures described within PHP code. The most common delimiters are <?php to open and ?> to close PHP sections. <script language="php"> and </script> delimiters are also available, as are the shortened forms <? or <?= (which is used to echo back a string or variable) and ?> as well as ASP-style short forms <% or <%= and %>. While short delimiters are used, they make script files less portable as their purpose can be disabled in the PHP configuration, and so they are discouraged.[47] The purpose of all these delimiters is to separate PHP code from non-PHP code, including HTML.[48]

The first form of delimiters, <?php and ?>, in XHTML and other XML documents, creates correctly formed XML 'processing instructions'.[49] This means that the resulting mixture of PHP code and other markup in the server-side file is well-formed XML.

Variables are prefixed with a dollar symbol and a type does not need to be specified in advance. Unlike function and class names, variable names are case sensitive. Both double-quoted ("") and heredoc strings allow the ability to embed a variable's value into the string.[50] PHP treats newlines as whitespace in the manner of a free-form language (except when inside string quotes), and statements are terminated by a semicolon.[51] PHP has three types of comment syntax: /* */ marks block and inline comments; // as well as # are used for one-line comments.[52] The echo statement is one of several facilities PHP provides to output text (e.g. to a web browser).

In terms of keywords and language syntax, PHP is similar to most high level languages that follow the C style syntax. If conditions, for and while loops, and function returns are similar in syntax to languages such as C, C++, Java and Perl.

Data types

PHP stores whole numbers in a platform-dependent range. This range is typically that of 32-bit signed integers. Unsigned integers are converted to signed values in certain situations; this behavior is different from other programming languages.[53] Integer variables can be assigned using decimal (positive and negative), octal, and hexadecimal notations. Floating point numbers are also stored in a platform-specific range. They can be specified using floating point notation, or two forms of scientific notation.[54] PHP has a native Boolean type that is similar to the native Boolean types in Java and C++. Using the Boolean type conversion rules, non-zero values are interpreted as true and zero as false, as in Perl and C++.[54] The null data type represents a variable that has no value. The only value in the null data type is NULL.[54] Variables of the "resource" type represent references to resources from external sources. These are typically created by functions from a particular extension, and can only be processed by functions from the same extension; examples include file, image, and database resources.[54] Arrays can contain elements of any type that PHP can handle, including resources, objects, and even other arrays. Order is preserved in lists of values and in hashes with both keys and values, and the two can be intermingled.[54] PHP also supports strings, which can be used with single quotes, double quotes, or heredoc syntax.[55]

The Standard PHP Library (SPL) attempts to solve standard problems and implements efficient data access interfaces and classes.[56]


PHP has hundreds of base functions and thousands more via extensions. These functions are well documented on the PHP site; however, the built-in library has a wide variety of naming conventions and inconsistencies. PHP currently has no functions for thread programming, although it does support multiprocess programming on POSIX systems.[57]

5.2 and earlier

Functions are not first-class functions and can only be referenced by their name, directly or dynamically by a variable containing the name of the function. [58] User-defined functions can be created at any time without being prototyped.[58] Functions can be defined inside code blocks, permitting a run-time decision as to whether or not a function should be defined. Function calls must use parentheses, with the exception of zero argument class constructor functions called with the PHP new operator, where parentheses are optional. PHP supports quasi-anonymous functions through the create_function() function, although they are not true anonymous functions because anonymous functions are nameless, but functions can only be referenced by name, or indirectly through a variable $function_name();, in PHP.[58]

5.3 and newer

PHP gained support for closures. True anonymous functions are supported using the following syntax:

function getAdder($x)
    return function ($y) use ($x) {
        return $x + $y;
$adder = getAdder(8);
echo $adder(2); // prints "10"

Here, getAdder() function creates a closure using parameter $x (keyword "use" forces getting variable from context), which takes additional argument $y and returns it to the caller. Such a function can be stored, given as the parameter to other functions, etc. For more details see Lambda functions and closures RFC.

The goto flow control device was made available in PHP 5.3 and is used as follows:

function lock()
    $file = fopen("file.txt","r+");
        fwrite($file, "Success!");
        return 0;
        goto retry;

When lock() is called, PHP opens a file and tries to lock it. retry:, the target label, defines the point to which execution should return if flock() is unsuccessful and the goto retry; is called. goto is not unrestricted and requires that the target label be in the same file and context.


Basic object-oriented programming functionality was added in PHP 3 and improved in PHP 4.[3] Object handling was completely rewritten for PHP 5, expanding the feature set and enhancing performance.[59] In previous versions of PHP, objects were handled like primitive types.[59] The drawback of this method was that the whole object was copied when a variable was assigned or passed as a parameter to a method. In the new approach, objects are referenced by handle, and not by value. PHP 5 introduced private and protected member variables and methods, along with abstract classes and final classes as well as abstract methods and final methods. It also introduced a standard way of declaring constructors and destructors, similar to that of other object-oriented languages such as C++, and a standard exception handling model. Furthermore, PHP 5 added interfaces and allowed for multiple interfaces to be implemented. There are special interfaces that allow objects to interact with the runtime system. Objects implementing ArrayAccess can be used with array syntax and objects implementing Iterator or IteratorAggregate can be used with the foreach language construct. There is no virtual table feature in the engine, so static variables are bound with a name instead of a reference at compile time.[60]

If the developer creates a copy of an object 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 the object's properties. If a __clone() method is defined, then it will be responsible for setting the necessary properties in the created object. For convenience, the engine will supply a function that imports the properties of the source object, so that the programmer can start with a by-value replica of the source object and only override properties that need to be changed.[61]

Speed optimization

As with any interpreted language, PHP scripts are stored as human-readable source code and are compiled on-the-fly by the PHP engine.[62][63] In order to speed up execution time and not have to compile the PHP source code every time the webpage is accessed, PHP scripts can also be stored in binary format using PHP compilers such as phc and roadsend.

Code optimizers aim to reduce the runtime of the compiled code by reducing its size and making other changes that can reduce the execution time with the goal of improving performance. The nature of the PHP compiler is such that there are often opportunities for code optimization,[64] and an example of a code optimizer is the eAccelerator PHP extension.[65]

Another approach for reducing overhead for high load PHP servers is using an Opcode cache. Opcode caches work by caching the compiled form of a PHP script (opcodes) in shared memory to avoid the overhead of parsing and compiling the code every time the script runs. An opcode cache, APC, will be built into PHP 6.[66] Opcode caching is also available in Zend Server Community Edition.


PHP includes free and open source libraries with the core build. PHP is a fundamentally Internet-aware system with modules built in for accessing FTP servers, many database servers, embedded SQL libraries such as embedded PostgreSQL, MySQL and SQLite, LDAP servers, and others. Many functions familiar to C programmers such as those in the stdio family are available in the standard PHP build.[67]

PHP allows developers to write extensions in C to add functionality to the PHP language. These can then be compiled into PHP or loaded dynamically at runtime. Extensions have been written to add support for the Windows API, process management on Unix-like operating systems, multibyte strings (Unicode), cURL, and several popular compression formats. Some more unusual features include integration with Internet Relay Chat, dynamic generation of images and Adobe Flash content, and even speech synthesis. The PHP Extension Community Library (PECL) project is a repository for extensions to the PHP language.[68]

Zend provides a certification exam for programmers to become certified PHP developers.

See also


  1. ^ a b c Rasmus Lerdorf began assembling C code originally written for CGI scripts into a library and accessing the library's functions, including SQL queries, through HTML-embedded commands in 1994; by 1995 the commands had taken the shape of PHP code that would be familiar of users of the language today. Lerdorf, Rasmus (2007-04-26). "PHP on Hormones - history of PHP presentation by Rasmus Lerdorf given at the MySQL Conference in Santa Clara, California" (mp3). The Conversations Network. Retrieved 2009-12-11. "Every day I would change the language drastically, and it didn't take very long, so by 1995, mid-1995 or so, PHP looked like this. This isn't that far from what PHP looks like today, actually." 
  2. ^ "PHP Snapshots". The PHP Group. Retrieved 2008-06-18. 
  3. ^ a b c d e f g h i j k l "History of PHP and related projects". The PHP Group. Retrieved 2008-02-25. 
  4. ^ "GPL-Incompatible, Free Software Licenses". Various Licenses and Comments about Them. Free Software Foundation. Retrieved 2008-02-22. 
  5. ^ Lerdorf, Rasmus (2007-04-26). "PHP on Hormones" (mp3). The Conversations Network. Retrieved 2009-06-22. 
  6. ^ Lerdorf, Rasmus (2007). "Slide 3". slides for 'PHP on Hormones' talk. The PHP Group. Retrieved 2009-06-22. 
  7. ^ Lerdorf, Rasmus (1995-06-08). "Announce: Personal Home Page Tools (PHP Tools)". comp.infosystems.www.authoring.cgi. (Web link). Retrieved on 2006-09-17.
  8. ^ "Zend Engine version 2.0: Feature Overview and Design". Zend Technologies Ltd.. Retrieved 2006-09-17. 
  9. ^ a b " 2007 news archive". The PHP Group. 2007-07-13. Retrieved 2008-02-22. 
  10. ^ Kerner, Sean Michael (2008-02-01). "PHP 4 is Dead—Long Live PHP 5". InternetNews. Retrieved 2008-03-16. 
  11. ^ Trachtenberg, Adam (2004-07-15). "Why PHP 5 Rocks!". O'Reilly. Retrieved 2008-02-22. 
  12. ^ "Late Static Binding in PHP". Digital Sandwich. 2006-02-23. Retrieved 2008-03-25. 
  13. ^ "Static Keyword". The PHP Group. Retrieved 2008-03-25. 
  14. ^ "Using Register Globals". PHP. Retrieved 2008-04-04. 
  15. ^ "Prepare for PHP 6". CorePHP. 2005-11-23. Retrieved 2008-03-24. 
  16. ^ "PHP 5.3 migration guide". The PHP project. Retrieved 2009-07-03. 
  17. ^ "GoPHP5" (HTML). 
  18. ^ GoPHP5. "PHP projects join forces to Go PHP 5" (PDF). GoPHP5 Press Release. Retrieved 2008-02-23. 
  19. ^ "GoPHP5". GoPHP5. Retrieved 2008-02-22. 
  20. ^ "Unicode". The PHP Group. Retrieved 2008-03-25. 
  21. ^ Byfield, Bruce (February 28, 2007). "Upcoming PHP release will offer Unicode support". Retrieved 2009-06-23. 
  22. ^ The PHP Group. "PHP For Windows snapshots". PHP Windows Development Team. Retrieved 2009-05-25. 
  23. ^ a b c d e "PHP: PHP 4 ChangeLog". The PHP Group. 2008-01-03. Retrieved 2008-02-22. 
  24. ^ "PHP: Using PHP from the command line - Manual:". The PHP Group. Retrieved 2009-09-11. 
  25. ^ "4.4.8 Release Announcement". PHP. 2008-08-08. Retrieved 2009-07-29. 
  26. ^ "Downloads". PHP. Retrieved 2009-07-29. 
  27. ^ "4.4.9 Release Announcement". PHP. Retrieved 2009-07-29. 
  28. ^ a b c "PHP: PHP 5 ChangeLog". The PHP Group. 2007-11-08. Retrieved 2008-02-22. 
  29. ^ "Embedding PHP in HTML". O'Reilly. 2001-05-03. Retrieved 2008-02-25. 
  30. ^ "What does PHP do?". The PHP Group. Retrieved 2008-02-25. 
  31. ^ "PHP and MySQL". University of Alabama. Retrieved 2008-02-25. 
  32. ^ "PHP Server-Side Scripting Language". Indiana University. 2007-04-04. Retrieved 2008-02-25. 
  33. ^ "JavaServer Pages Technology — JavaServer Pages Comparing Methods for Server-Side Dynamic Content White Paper". Sun Microsystems. Retrieved 2008-02-25. 
  34. ^ "PHP: PHP Usage Stats". SecuritySpace. 2007-04-01. Retrieved 2008-02-24. 
  35. ^ "PHP and Facebook | Facebook". Retrieved 2009-07-29. 
  36. ^ "Manual:Installation requirements#PHP". MediaWiki. 2010-01-25. Retrieved 2010-02-26. "PHP is the programming language in which MediaWiki is written [...]" 
  37. ^ "About WordPress". Retrieved 2010-02-26. "WordPress was [...] built on PHP" 
  38. ^ "Moodle - About". Retrieved 2009-12-20. 
  39. ^ "PHP-related vulnerabilities on the National Vulnerability Database". 2008-03-01. 
  40. ^ "Security and... Driving? (and Hiring) - Sean Coates: PHP, Web (+Beer)". Sean Coates. Retrieved 2009-07-29. 
  41. ^ Interview: Ivo Jansch, February 26, 2008
  42. ^ "PHP Taint Mode RFC". 
  43. ^ "Developer Meeting Notes, Nov. 2005". 
  44. ^ "Taint mode decision, Nov 2007". 
  45. ^ "The Power of PHP, both Good and Evil". 2009-02-28. 
  46. ^ "Hardened-PHP Project". 2008-08-15. 
  47. ^ "PHP: Basic syntax". The PHP Group. Retrieved 2008-02-22. 
  48. ^ "Your first PHP-enabled page". The PHP Group. Retrieved 2008-02-25. 
  49. ^ Bray, Tim; et al (26 November 2008). "Processing Instructions". Extensible Markup Language (XML) 1.0 (Fifth Edition). W3C. Retrieved 2009-06-18. 
  50. ^ "Variables". The PHP Group. Retrieved 2008-03-16. 
  51. ^ "Instruction separation". The PHP Group. Retrieved 2008-03-16. 
  52. ^ "Comments". The PHP Group. Retrieved 2008-03-16. 
  53. ^ "Integers in PHP, running with scissors, and portability". MySQL Performance Blog. March 27, 2007. Retrieved 2007-03-28. 
  54. ^ a b c d e "Types". The PHP Group. Retrieved 2008-03-16. 
  55. ^ "Strings". The PHP Group. Retrieved 2008-03-21. 
  56. ^ "SPL — StandardPHPLibrary". March 16, 2009. Retrieved 2009-03-16. 
  57. ^ "PHP.NET: Process Control". Retrieved 2009-08-06. 
  58. ^ a b c "Functions". The PHP Group. Retrieved 2008-03-16. 
  59. ^ a b "PHP 5 Object References". mjtsai. Retrieved 2008-03-16. 
  60. ^ "Classes and Objects (PHP 5)". The PHP Group. Retrieved 2008-03-16. 
  61. ^ "Object cloning". The PHP Group. Retrieved 2008-03-16. 
  62. ^ "How do computer languages work?". Retrieved 2009-11-04. 
  63. ^ (Gilmore 2006, p. 43)
  64. ^ "PHP Accelerator 1.2 (page 3, Code Optimisation)" (PDF). Nick Lindridge. Retrieved 2008-03-28. 
  65. ^ "eAccelerator". Retrieved 2009-09-18. 
  66. ^ "Upcoming PHP6 Additions & Changes". Retrieved 2009-09-18. 
  67. ^ "PHP Function List". The PHP Group. Retrieved 2008-02-25. 
  68. ^ "Developing Custom PHP Extensions". devnewz. 2002-09-09. Retrieved 2008-02-25. 

External links

Study guide

Up to date as of January 14, 2010
(Redirected to Topic:PHP article)

From Wikiversity


Welcome to Wikiversity's home for PHP!

PHP (wiktionary | wikipedia | wikibooks)
Portal:Engineering and Technology —> School:Computer Science —> Topic:Computer Programming —> Topic:PHP

PHP is a high level, dynamic, interpreted scripting language. It augments raw HTML by allowing significant interactivity and increased functionality. It has become popular in recent years as it is easy to begin working with and supported by a good majority of web hosting companies. MediaWiki, the server software for Wikiversity, makes extensive use of PHP.


Before starting the course, we suggest you go over the following:

Course Description

The course will help you learn PHP by going over material step by step and explaining relevant concepts. Reference materials will be complemented by learning guides, which will expand on the reference by elaborating the how and why of each topic.



Learning guides

Further reading


If you are interested in learning PHP with a mentor, list yourself below by adding a *~~~~

  • Example 12:44, 14 January 2010 (UTC)
  • Gibrel 00:22, 10 October 2006 (UTC)
  • Jak08 21:50, 20 October 2006 (UTC)Jak08
  • Diegoramos 20:16, 10 November 2006 (UTC)
  • Xora 18:45, 9 April 2007 (UTC)
  • Josh Sandlin 20:27, 6 November 2007 (UTC)
  • Shinrin 18:43, 10 July 2008 (UTC)
  • Himanshu 14:53, 4 Janauary 2009 (UTC)
  • dako3256 21:08, 23 October 2009 (UTC)
  • Sparcle z 09:55, 30 October 2009 (UTC)

External links


Up to date as of January 15, 2010

Definition from Wiktionary, a free dictionary




Originally an Initialism of personal home page, used to describe a set of tools written by Rasmus Lerdorf in 1995; later inherited by other software built to implement similar functionality, with the new recursive expansion PHP: hypertext preprocessor.

Proper noun




  1. (programming languages) A scripting language widely used to write web applications.

See also



Up to date as of January 23, 2010
(Redirected to PHP Programming article)

From Wikibooks, the open-content textbooks collection


What is PHP?

PHP is a scripting language designed to fill the gap between SSI (Server Side Includes) and Perl, intended largely for the web environment. PHP has gained quite a following in recent times, and it is one of the forerunners in the Open Source software movement. Its popularity derives from its C-like syntax, its speed and its simplicity. PHP is currently divided into two major versions: PHP 4 and PHP 5, although PHP 4 is deprecated and is no longer developed or supplied with critical bug fixes. PHP 6 is currently under development.

If you've ever been to a website that needs you to login, you've probably encountered a server-side scripting language. Due to its market saturation, this means you've probably come across PHP. PHP was designed by Rasmus Lerdorf to display his resume online and to collect data from his visitors.

Basically, PHP allows a static web document to become dynamic. "PHP" is a recursive acronym that stands for "PHP: Hypertext Preprocessor". PHP preprocesses (that is, PHP processes before the output is sent to the browser) hypertext documents. Because of this, the pages can change before the user sees them, based on conditions. This can be used to write something to the page, create a table with a number of rows equal to the number of times the user has visited, or integrate the web page with a web database, such as MySQL.

Before you embark on the wonderful journey of Server Side Processing, it is recommended that you have some basic understanding of the HyperText Markup Language. PHP is also being used to build GUI-driven applications; PHP-GTK is used to build Graphical User Interfaces.

Setup and Installation

Note: Before contributing, check out the discussion page. How to write your examples.

Learning the Language

The Basics

This section is about things that are important for any type of PHP development. Useful for a PHP programmer of any level.
  1. Beginning with "Hello World!" Development stage: 100% (as of 10 Feb 2006)(10 Feb 2006)
  2. Nuts and Bolts Development stage: 75% (as of 14 Jan 2006)(14 Jan 2006)
  3. Commenting and Style Development stage: 100% (as of 14 Jan 2006)(14 Jan 2006)
  4. Arrays Development stage: 75% (as of 10 Feb 2006)(10 Feb 2006)
  5. Control structures
    1. The if Structure Development stage: 75% (as of 19 Mar 2009)(19 Mar 2009)
    2. The switch Structure Development stage: 75% (as of 14 Jan 2006)(14 Jan 2006)
    3. The while Loop Development stage: 75% (as of 14 Jan 2006)(14 Jan 2006)
    4. The do while Loop Development stage: 50% (as of 14 Jan 2006)(14 Jan 2006)
    5. The for Loop Development stage: 50% (as of 14 Jan 2006)(14 Jan 2006)
    6. The foreach Loop Development stage: 75% (as of 14 Jan 2006)(14 Jan 2006)
  6. Functions Development stage: 75% (as of 10 Feb 2006)(10 Feb 2006)
  7. Files Development stage: 100% (as of 12 Feb 2008)(12 Feb 2008)
  8. Mailing Development stage: 50% (as of 14 Jan 2006)(14 Jan 2006)
  9. Cookies Development stage: 75% (as of 14 Jan 2006)(14 Jan 2006)
  10. Sessions Development stage: 75% (as of 2008-05-07)(2008-05-07)
  11. Databases
    1. MySQL Development stage: 75% (as of 14 Jan 2006)(14 Jan 2006)
    2. PostgreSQL Development stage: 25% (as of 18 Apr 2009)(18 Apr 2009)
    3. PHP Data Objects Development stage: 00% (as of 18 Dec 2006)(18 Dec 2006)
  12. Integration Methods (HTML Forms, etc.) Development stage: 75% (as of 14 Jan 2006)(14 Jan 2006)

Advanced PHP

Advanced PHP includes high level programming and PHP techniques designed to make PHP even more useful and powerful.

Object Oriented Programming (OOP)

  1. Classes
  2. Special Methods
  3. Class Extensions (Inheritance)
  4. The SSH Class


  1. Why Templating
  2. Templates
  3. Caching
  4. SMARTY templating system
  5. PRADO Component Framework
  6. Flat Frog templating system Development stage: 25% (as of 23 march 2006)(23 march 2006)
  7. XSL





  1. Configuration: Register Globals
  2. SQL Injection Attacks
  3. Cross Site Scripting Attacks
  4. Building a secure user login system

See also the section on avoiding session fixation in the Sessions chapter.

Command-Line Interface (CLI)

  1. PHP CLI
  2. PHP-GTK
  3. Daemonization

Code Snippets

Useful for any beginners to learn code from.

PHP 4 & 5

Basic Level

  • echo "the text to print"; - This language construct will echo the text between the quotes. This is not a function but a language construct.
  • echo "$var"; - Notice the double quotation marks. Because double quotation marks are used, this will print the value of the variable. If $var="Bobby", this will output:


  • echo '$var'; - Notice that the quotation marks are now single. This will output the literal keystrokes inside the quotes. The example will output:


  • $var="Jericho";echo "Joshua fit the battle of $var."; - Other than substituting the value of a variable for the variable name (and one or two other minor items), double quotes will quote literal keystrokes. So this will output:

Joshua fit the battle of Jericho.

Again, if single quotes were used — 'Joshua fit the battle of $var'; — this would output:

Joshua fit the battle of $var.

  • echo $var; - If you only want to print the value of a variable, you don't need quotes at all. If the value of $var is "1214", the code will output:


  • require "url"; - This language construct will include the page between the quotes. Can NOT be used with dynamic pages, e.g. require("main.php?username=SomeUser"); would not work. This is not a function but a language construct.
  • date("Date/time format"); - Function which returns a date from a Unix Timestamp - where H is the hour, i is the minutes, s is the seconds, d is the day, m is the month and Y is the year in four digits - e.g. date("H:i:s d/m/Y"); would return 12:22:01 10/08/2006 on 10th August 2006 at 12:22:01.
  • unlink("filename"); - Function which deletes the file specified in filename.


Basic Level

  $variable1 = 'beginning';
  //This is a comment after a variable being defined
  if ($variable1 == 'beginning') {
    //If is a test to see if a variable has certain
    //value and initiates the wanted sequences if true
    echo 'Hello World!';
    //The echo displays to the page


Include OOP based examples, made by experienced developer

PHP 5 Only

Basic Level

Basics, working only on PHP 5.

  • file_put_contents("filename", "Text to save"); - Functions which saves the text specified in Text to save to the file specified in filename. Will overwrite existing file contents unless another parameter FILE_APPEND is added.

E.g. file_put_contents("filename", "Text to save"); will write Text to save to filename, but will overwrite existing text whereas file_put_contents("filename", "Text to save", FILE_APPEND); will write Text to save to filename, but will not overwrite existing text (instead it appends).


  1. Input validation by Kgrsajid.
  2. Advanced Input validation by nemesiskoen.


For reviews of numerous PHP editors, see PHP-editors.



Jatkins: PHP 4 & 5 examples, and PHP 5 only examples.
Douglas Clifton: New editor. Hoping to add more soon!
James Booker: Minor corrections. Hoping to add more content in time.
Spoom: Original for and articles, various reformatting and additions.
IBB: See profile.
Kander: Minor edits to the PHP and MySQL section.
Qrc: Started initial page for Configuration:Register Globals.
Bumppo: Started object-oriented PHP section
programmabilities: Minor edits.
ahc: Significant editing to existing sections.
Liu Chang: Added "Setting up PHP" section. Hoping to add more in time
Monkeymatt: Fixed some typos, fixed the templating section.
Charles Iliya Krempeaux: Added PHP CLI section. Minor cleanups on existing sections. Added PHP-GTK section.
scorphus: Fixes in installation procedures on Debian systems (to conform standards - we now use aptitude)
immortalgeek: Added some php web links to Resource section.
Wykis: Working on Smarty section, foreach, arrays, sessions, all basic programming
Bolo: working on Flat Frog section.
KGR Sajid: PHP5 editor. Also edited some other minor things.
banzaimonkey: Formatting changes and editing.
Meemo: Some small edits, fixing a few scripts and the spelling of Rumpelstiltskin. ;)
Justin Kestelyn: Added a link in Resources.
Sam Wilson: Elaboration on session fixation.

Simple English

Hypertext Preprocessor

Latest release:5.3.4[1] / December 10, 2010

License:PHP licence

PHP (PHP: Hypertext Preprocessor) is a scripting language that helps make webpages more interactive, by allowing them to do more things. For example, a website programmed with PHP can have pages that are password protected, whereas a website with no programming can not do this. Standard PHP file extensions are: .php .php3 or .phtml, although you can tell a webserver to use any extension.[2] Its structure was influenced by many languages like C, Perl, Java, C++, and even Python. It is considered to be free software by mean of the Free Software Foundation[3].

Wikipedia, which runs on MediaWiki, uses the PHP scripting language. [4]



PHP was first created by a man called Rasmus Lerdorf in 1995. It is now developed and improved by a large team of people.


An example Hello World program:

Hello, World!


  1. PHP:Downloads
  2. Retrieved on 30 October, 2007
  3. "GPL-Incompatible, Free Software Licenses". Various Licenses and Comments about Them. Free Software Foundation. 
  4. Simple English Wikipedia version page, the version of PHP that Wikipedia runs on, under the "Installed software" heading.

Other websites

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