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Copyright 1997 - 2017 by the PHP Documentation Group. This material may be distributed only subject to the terms and conditions set forth in the Creative Commons Attribution 3.0 License or later. |
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A copy of the Creative Commons Attribution 3.0 license is distributed with this manual. The latest version is presently available at. |
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If you are interested in redistribution or republishing of this document in whole or in part, either modified or unmodified, and you have questions, please contact the Copyright holders at. Note that this address is mapped to a publicly archived mailing list. |
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PHP, which stands for "PHP: Hypertext Preprocessor" is a widely-used Open Source general-purpose scripting language that is especially suited for web development and can be embedded into HTML. |
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Its syntax draws upon C, Java, and Perl, and is easy to learn. The main goal of the language is to allow web developers to write dynamically generated web pages quickly, but you can do much more with PHP. |
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This manual consists primarily of a function reference, but also contains a language reference, explanations of some of PHP's major features, and other supplemental information. You can download this manual in several formats at. |
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More information about how this manual is developed can be found in the 'About the manual' appendix. If you are interested in the history of PHP, visit the relevant appendix. We highlight the currently most active people on front page of the manual, but there are many more contributors who currently help in our work or have provided a great amount of help to the project in the past. |
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There are a lot of unnamed people who help out with user notes on manual pages, which continually get included in the references, the work of whom we are also very thankful for. |
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All of the lists provided below are in alphabetical order. PHP (recursive acronym for PHP: Hypertext Preprocessor) is a widely-used open source general-purpose scripting language that is especially suited for web development and can be embedded into HTML. Nice, but what does that mean? |
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Instead of lots of commands to output HTML (as seen in C or Perl), PHP pages contain HTML with embedded code that does "something" (in this case, output "Hi, I'm a PHP script!"). |
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The PHP code is enclosed in special start and end processing instructions that allow you to jump into and out of "PHP mode." What distinguishes PHP from something like client-side JavaScript is that the code is executed on the server, generating HTML which is then sent to the client. |
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The client would receive the results of running that script, but would not know what the underlying code was. You can even configure your web server to process all your HTML files with PHP, and then there's really no way that users can tell what you have up your sleeve. |
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The best things in using PHP are that it is extremely simple for a newcomer, but offers many advanced features for a professional programmer. Don't be afraid reading the long list of PHP's features. |
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You can jump in, in a short time, and start writing simple scripts in a few hours. Although PHP's development is focused on server-side scripting, you can do much more with it. |
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Read on, and see more in the What can PHP do? section, or go right to the introductory tutorial if you are only interested in web programming. Anything. |
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PHP is mainly focused on server-side scripting, so you can do anything any other CGI program can do, such as collect form data, generate dynamic page content, or send and receive cookies. But PHP can do much more. Server-side scripting. This is the most traditional and main target field for PHP. |
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You need three things to make this work: the PHP parser (CGI or server module), a web server and a web browser. You need to run the web server, with a connected PHP installation. You can access the PHP program output with a web browser, viewing the PHP page through the server. |
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All these can run on your home machine if you are just experimenting with PHP programming. See the installation instructions section for more information. Command line scripting. You can make a PHP script to run it without any server or browser. You only need the PHP parser to use it this way. |
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This type of usage is ideal for scripts regularly executed using cron (on *nix or Linux) or Task Scheduler (on Windows) These scripts can also be used for simple text processing tasks. See the section about Command line usage of PHP for more information. Writing desktop applications. |
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PHP is probably not the very best language to create a desktop application with a graphical user interface, but if you know PHP very well, and would like to use some advanced PHP features in your client-side applications you can also use PHP-GTK to write such programs. |
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You also have the ability to write cross-platform applications this way. PHP-GTK is an extension to PHP, not available in the main distribution. If you are interested in PHP-GTK, visit. PHP can be used on all major operating systems, including Linux, many Unix variants (including HP-UX, Solaris and OpenBSD), Microsoft Windows, Mac OS X, RISC OS, and probably others. |
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PHP has also support for most of the web servers today. This includes Apache, IIS, and many others. And this includes any web server that can utilize the FastCGI PHP binary, like lighttpd and nginx. |
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PHP works as either a module, or as a CGI processor. So with PHP, you have the freedom of choosing an operating system and a web server. Furthermore, you also have the choice of using procedural programming or object oriented programming (OOP), or a mixture of them both. With PHP you are not limited to output HTML. |
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PHP's abilities includes outputting images, PDF files and even Flash movies (using libswf and Ming) generated on the fly. You can also output easily any text, such as XHTML and any other XML file. PHP can autogenerate these files, and save them in the file system, instead of printing it out, forming a server-side cache for your dynamic content. PHP also has support for talking to other services using protocols such as LDAP, IMAP, SNMP, NNTP, POP3, HTTP, COM (on Windows) and countless others. |
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You can also open raw network sockets and interact using any other protocol. PHP has support for the WDDX complex data exchange between virtually all Web programming languages. Talking about interconnection, PHP has support for instantiation of Java objects and using them transparently as PHP objects. |
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PHP has useful text processing features, which includes the Perl compatible regular expressions (PCRE), and many extensions and tools to parse and access XML documents. PHP standardizes all of the XML extensions on the solid base of libxml2, and extends the feature set adding SimpleXML, XMLReader and XMLWriter support. |
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And many other interesting extensions exist, which are categorized both alphabetically and by category. And there are additional PECL extensions that may or may not be documented within the PHP manual itself, like XDebug. As you can see this page is not enough to list all the features and benefits PHP can offer. |
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Read on in the sections about installing PHP, and see the function reference part for explanation of the extensions mentioned here. When PHP parses a file, it looks for opening and closing tags, which are which tell PHP to start and stop interpreting the code between them. |
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Parsing in this manner allows PHP to be embedded in all sorts of different documents, as everything outside of a pair of opening and closing tags is ignored by the PHP parser. PHP also allows for short open tag (which is discouraged since it is only available if enabled using the short_open_tag php.ini configuration file directive, or if PHP was configured with the --enable-short-tags option). |
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If a file is pure PHP code, it is preferable to omit the PHP closing tag at the end of the file. This prevents accidental whitespace or new lines being added after the PHP closing tag, which may cause unwanted effects because PHP will start output buffering when there is no intention from the programmer to send any output at that point in the script. |
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Everything outside of a pair of opening and closing tags is ignored by the PHP parser which allows PHP files to have mixed content. This allows PHP to be embedded in HTML documents, for example to create templates. |
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In this example PHP will skip the blocks where the condition is not met, even though they are outside of the PHP open close tags; PHP skips them according to the condition since the PHP interpreter will jump over blocks contained within a condition that is not met. |
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For outputting large blocks of text, dropping out of PHP parsing mode is generally more efficient than sending all of the text through echo or print. The other two are short tags and ASP style tags. As such, while some people find short tags and ASP style tags convenient, they are less portable, and generally not recommended. |
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Short tags (example three) are only available when they are enabled via the short_open_tag php.ini configuration file directive, or if PHP was configured with the --enable-short-tags option. ASP style tags (example five) are only available when they are enabled via the asp_tags php.ini configuration file directive, and have been removed in PHP 7.0.0. |
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Using short tags should be avoided when developing applications or libraries that are meant for redistribution, or deployment on PHP servers which are not under your control, because short tags may not be supported on the target server. For portable, redistributable code, be sure not to use short tags. |
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As in C or Perl, PHP requires instructions to be terminated with a semicolon at the end of each statement. The closing tag of a block of PHP code automatically implies a semicolon; |
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you do not need to have a semicolon terminating the last line of a PHP block. The closing tag for the block will include the immediately trailing newline if one is present. |
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The closing tag of a PHP block at the end of a file is optional, and in some cases omitting it is helpful when using include or require, so unwanted whitespace will not occur at the end of files, and you will still be able to add headers to the response later. |
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It is also handy if you use output buffering, and would not like to see added unwanted whitespace at the end of the parts generated by the included files. |
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