Introduction to PHP
PHP: Stands for Hypertext Preprocessor.
one of the world's most popular server-side scripting languages for building
dynamic, data-driven Web applications and can be embedded into HTML.
is a scripting language, as opposed to a compiled language. This means that PHP
is designed to do something only after an event occurs for example when a user
submits a form or goes to a URL (Uniform Resource Locator the technical term
for a Web address). These languages can also be described as interpreted,
because the code must be run through an executable, such as the PHP module or
compiled languages such as C and C++ can be used to write stand-alone
applications that can act independently of any event. You should also
understand that PHP is a server-side technology. This refers to the fact that
everything PHP does occur on the server (as opposed to on the client, which is
the computer being used by the person viewing the Web site).
is just a computer set up to provide the pages you see when you go to a Web
address with your browser (for example, Firefox, Microsoft Internet Explorer,
PHP is cross-platform, meaning that it can be used on machines running Unix,
Windows, Macintosh, and other operating systems.
we’re talking about the server’s operating system, not the client’s. Not only
can PHP run on almost any operating system, but, unlike many other programming
languages, it enables you to switch your work from one platform to another with
few or no modifications.
this tutorial, we describe the basics of PHP scripts and the rules that
apply to all PHP statements. Consider these rules similar to
general grammar and punctuation rules. In the remaining tutorial, you find
out about specific PHP statements and features and how to write PHP
scripts to perform specific tasks
is much easier to learn and use.
was written specifically for dynamic Web page creation.
is both free and cross-platform.
is the most popular tool available for developing dynamic Web sites.
you are not limited to output by HTML but include other outputting methods
like 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.
of the strongest and most significant features of PHP is its support for
a wide range of databases. Writing a database-enabled web page is
incredibly simple by using one of the database-specific extensions (e.g., MySQL),
using an abstraction layer like PDO, or connecting to any database supporting
the Open Database Connection standard via the ODBC extension.
Other databases may utilize cURL or sockets, like CouchDB.
also has support for talking to other services using protocols such as
LDAP, IMAP, SNMP, NNTP, POP3, HTTP, COM (on Windows), and countless
others. 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.
has support for the instantiation of Java objects and using them
transparently as PHP objects.
has useful text processing features, which include Perl-compatible
regular expressions (PCRE), and many extensions and tools to parse
and access XML documents.
can be used on all major operating systems, including Linux, many
Unix variants (including HP-UX, Solaris, and OpenBSD), Microsoft Windows,
macOS, RISC OS, and probably others.
also has 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. 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.
The PHP program works with the web server, which is
the program that delivers web pages to the world. After you type a
URL into your web browser’s address bar, you’re sending a message to the
internet server at that URL, inquiring it to send you an
HTML file. The web server responds by sending
the asked file. Your browser reads the
HTML file and shows the web page. You to ask for
a file from the web server when
you click a link on a web page. In addition, the
web server forms a file when you click a web
page button that submits a form.
This handle is basically the same when PHP
is installed. You request a file, the web server
happens to be running PHP, and it sends HTML back to the browser, much
obliged to the programming in PHP.
can PHP do?
PHP scripts are
used in three main areas.
scripting. This is the most traditional and main target
field for PHP. 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. All these
can run on your home machine if you are just experimenting with PHP
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.
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
desktop applications. 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.
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.