Introduction to PHP

Introduction to PHP Lesson 3

PHP is the most popular web development language in the world • PHP sources of Information • http://php.net • http://www.zend.com • http://www.hostscripts.com • PHP: Hypertext Preprocessor • PHP dealt with before HTML • Lies between web server and HTML • Interpreted language (i.e. not compiled) • Code is interpreted on the fly • Code is in plain text, so anyone with access to the web serves can view it • However, code can still be encrypted so it can’t be stolen. Sites that offer facilities for encryption include http://www.zend.com and IOnQ

PHP Programming standards • Goal is to make code easy to read and understand • However, there is NO accepted industry coding standards • Each programmer is encouraged to come up with his own standard or if he’s a part of a company and the company has its own standard then he is required to follow that standard.

Use Comments • Use comments but don’t comment everything because that would required a huge amount of time. // # /* .. */ Single line comment Multi- Line comment • Better if just make the code readable and simple • Also, use indentation

Embed PHP within HTML • If you need to create a page with few dynamic elements • Embed HTML with PHP • If you need to create a long complex PHP script

PHP Opening and Closing Tags • <?php….?> - this setting is always acceptable in any PHP configuration • <? …?> - this short_tag setting may not be available depending on your PHP config file (php.ini); make sure that in php.ini there is a line short_tag= on • <script language=“php”>…</script> - html style tag • <% … %> - ASP style tag

NOTE: • Each HTML browser may interpret some HTML tags in a different way. By embedding HTML within PHP you are assured that HTML will be interpreted in only 1 way. • However, if there is a need to change code and the programmer who will do it is not familiar with PHP then that would be a problem. So separate those parts that can be separated from PHP. • Ex. <html><head> tags…</body></html> • Note also that every PHP statement ends in a semi-colon (;)

Sample1 PHP program <html><body>// save as hello.php in your htdocs folder <?phpecho "Hello World!"; //you can also use print ?></body></html>

Sample2 PHP program <html><body>//save this as info.php in your htdocs folder<?phpphpinfo();?></body></html>

phpinfo() • is a php function that outputs information about your PHP settings: • Tells you the PHP version installed • Status of PHP Core variables • Note that there are local and Mastery Values. • The local value can be set on a page-by-page basis, by .htaccess file, or by a domain configuration. • The master value is the global setting as specified in the php.ini (of which only the System Administrators have access)

PHP Exercise 1: • Fix the errors in the PHP script (erroneous.php) open the link. Save you solution as my_solution_SURNAME.php erroneous.php

Introduction to PHP