An Introduction to PHP
"PHP is an open source general-purpose server-side scripting language originally designed for Web development to produce dynamic Web pages. It is one of the first developed server-side scripting languages to be embedded into an HTML source document rather than calling an external file to process data. The code is interpreted by a Web server with a PHP processor module which generates the resulting Web page. It also has evolved to include a command-line interface capability and can be used in standalone graphical applications. PHP can be deployed on most Web servers and also as a standalone shell on almost every operating system and platform free of charge. A competitor to Microsoft's Active Server Pages (ASP) server-side script engine and similar languages, PHP is installed on more than 20 million Web sites and 1 million Web servers. Software that uses PHP includes MediaWiki, Joomla, Wordpress, Concrete5, MyBB, and Drupal." (from wikipedia)
General Notes on PHP
The following provides a summary of what PHP is:
- PHP stands for PHP: Hypertext Preprocessor
- PHP is a server-side scripting language, like ASP, JSP, etc.
- PHP scripts run on the server.
- PHP supports many databases, e.g., MySQL, Oracle.
- PHP is an open source software.
How to Start Your First PHP Program?
WebDev supports PHP, so you don't need to
do anything on it, for example, installation or configuration.
The only thing you need to do is to create a .php
file in the php_web
directory. Note: you still
need to set correct permissions. To sumarize you can follow
the steps below:
- Create a .php file.
- Upload the .php file into the php_web folder.
- Set the permission for the php file:
ssh webdev cd php_web/ chmod 644 *.php
- Open your browser, input and visit the following address:
http://www.webdev.cs.uregina.ca/~your_cs_username/filename.php
Where to Write Your PHP Scripts?
PHP script always appears between a pair of symbols, <?php
and ?>
. For example,
<?php echo "<h1>Hello CS215 Students!<h1>"; echo "<p>Hi this is a sentence.</p>"; ?>
A PHP Server (WebDev) parses the PHP scripts and returns plain HTML
code back to the client browser. That is, the echo
function sends a level-one header (H1
) and a paragraph
(P
) to your browser. You can try this example on the web
server.
Anything outside those symbols in a PHP file is echoed automatically and may contain text, HTML tags and scripts, so your skills of HTML, CSS and JavaScript are usful in writing a .PHP file. The following PHP script is written mixed with HTML.
<!DOCTYPE html> <html> <head> <title>A Sample Php Program</title> </head> <body> <?php echo "<h1>Hello CS215 Students!<h1>"; ?> </body> </html>
Exercise 1
- Create and run a simple .php page on WebDev.
- To run .php programs on WebDev, type php filename.php at the WebDev prompt sign
- You can visit your php page by using the following url:
http://www.webdev.cs.uregina.ca/~your_cs_username/filename.php