PHP
PHP Overview
PHP is a widely-used general-purpose scripting language that is especially suited for Web development and can be embedded into HTML.
PHP was originally designed as a small set of Perl scripts, followed by a rewritten set of CGI binaries written in C by the Danish-Canadian programmer Rasmus Lerdorf in 1994 to display his résumé and to collect certain data, such as how much traffic his page was receiving. "Personal Home Page Tools" was publicly released on 8th June 1995 after Lerdorf combined it with his own Form Interpreter to create PHP/FI. Zeev Suraski and Andi Gutmans, two Israeli developers of the Technion - Israel Institute of Technology, rewrote the parser in 1997 and formed the base of PHP 3, changing the language's name to its current recursive form (PHP: Hypertext Preprocessor). The development team officially released PHP/FI 2 in November 1997 after months of beta testing. Public testing of PHP 3 began immediately 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. They also founded Zend Technologies in Ramat Gan, Israel which has since overseen the PHP advances. In May 2000, PHP 4, powered by the Zend Engine 1.0, was released. On July 13, 2004, PHP 5 was released, powered by Zend Engine II (formerly known as Zend Engine 2). PHP 5 includes new features such as PHP Data Objects (PDO) and more performance enhancements taking advantage of the new Zend Engine II.
SPSC Contributors: Peter Kroeger
Links
The PHP Group (www.php.net) is the primary PHP site for downloads, links and information. Zend Technologies also has a Developer Zone on their site.
For more links see http://www.php.net/links.php
Syntax
<?php ...PHP code... ?>
$variable_name
statements end with a ';'. Use { } to group statements.
if(expr) statement else statement
PHP Keywords
For a complete list see http://www.php.net/manual/en/reserved.php.
| keyword | purpose |
|---|---|
| break | |
| continue | |
| declare | |
| do-while | |
| echo() | outputs one or more strings |
| else | |
| elseif | |
| for | |
| foreach | |
| function | |
| if | |
| include() | includes and evaluates the specified file |
| include_once() | |
| return | |
| require() | |
| require_once() | |
| switch | |
| while |
*Note that keywords like echo() do not actually require () around its parameter(s).
PHP 5 Keywords
| keyword | purpose |
|---|---|
| class | |
| extends | |
| new | |
| var |
Ref
For a full reference see http://www.php.net/manual/en/langref.php.
Embedding in HTML
PHP is embedded inside HTML pages inside <?php and ?>.
Comments
PHP uses C/C++ style comments. // indicates the rest of the line is a comments. /* and */ indicate that all the text between them is a comment.
Variables
Variable begin with $ followed by a letter or underscore. Variable names are case sensitive and their type is determined by their context. Note than several reserved variables begin with underscore.
Examples
<html>
<head>
<title>PHP Test</title>
</head>
<body>
<?php echo '<p>Hello World</p>'; ?>
</body>
</html>
