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| Date post: | 16-Apr-2017 |
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Technology |
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Slide 2 of 38What are we going to cover?
What PHP is, what it can do and how it differs from HTML
How web servers work and the HTTP request-response lifecycle
Basic statements in PHP and an introduction to procedural programming and forms and databases overview
An overview to common PHP tools How to get more help with PHP
Slide 3 of 38What is PHP?
PHP: Hypertext preprocessor Server-side scripting language
(has to be run on a server, not in your browser like Javascript – that's a client-side language)
Open source and free to download(this means that the code behind PHP is freely available - this often means PHP hosting is cheaper than other platforms, such as ASP)
Particularly suitable for web applications, but doesn't have to be used for this purpose
Slide 4 of 38What can PHP do?
PHP is a general purpose scripting language. This means it can do lots of programming tasks. It is particularly suited to; Adding dynamic content to websites Processing HTML forms Connecting to databases and storing, searching
and retrieving information from databases Personalising and customising websites
Slide 5 of 38Why should I learn PHP?
To grow an evil army of programmers to take over the world MWHAHAHAHAHAHA… but seriously there are some good reasons
Easy to learn (difficult to master) Used widely in third party tools – WordPress,
Drupal, CiviCRM, Facebook applications etc Becoming much more mature and adopted as
an enterprise-level programming language
Slide 6 of 38
What do I need to get started with PHP?
Access to a web server with PHP installed This might be through a hosting company, and you
would access the server using an FTP program, like FileZilla. The files would be accessed from a URL likehttp://myurl.org/myfile.php
If you're more advanced, you might wish to have a go installing PHP on your own computer. There are builds available for Windows, most Linux variants and even MacOS. http://localhost/myfile.php
Slide 7 of 38
What do I need to get started with PHP (cont'd)
It helps to have a good understanding of how HTTP works (covered in this tutorial)
It helps to have at least a basic understanding of HTML (any version of HTML to be honest)
Your text editor of choice. Syntax highlighting is a great feature to have in a PHP editor. I use Eclipse, but there are many others to choose from;http://en.wikipedia.org/wiki/List_of_PHP_editors
Slide 8 of 38
Easy to learn, difficult to master
One of the great features of PHP is that it is easy to learn. It is also difficult to master; Writing maintainable code Reusable code (through objects) Designing applications to be secure Designing for scalability Designing for portability (between different
databases and server operating environments) There's always more to learn about PHP!!
Slide 9 of 38Why is PHP different to HTML?
HTML is static<html> <body> <h1>Hello world! </h1> </body></html>
Will always display 'Hello world!'
Slide 10 of 38
Why is PHP different to HTML? (cont'd)
PHP is dynamic<?php $greeting = 'Hola!';?><html> <body> <h1> <?php echo $greeting; ?> </h1> </body></html>
What will this display?
Slide 11 of 38How web servers work
So what makes PHP dynamic? Web servers and user agents (browsers) work
in what's called a 'client-server' relationship. The user agent (browser) sends a request to
the web server The web server interprets that request, and
sends a response to the web server
Slide 12 of 38How web servers work (cont'd)
User agent Browser – such as Firefox, Internet Explorer, Safari
– on a computer, mobile phone, iPhone or iPad etc Issues requests to a web server
For example, going to this URL in your browserhttp://www.example.com/index.phpcauses the browser to issue this request:
GET /index.php HTTP/1.1Host: www.example.com
Slide 13 of 38How web servers work (con'td)
Web server Many varieties of web server – such as IIS (Internet
information services), Apache httpd etc. PHP is primarily used with Apache httpd, but can be
used with IIS Interprets requests from a user agent, acts on
them and issues responses For example, a web server may respond to the
previous request with this:
Slide 14 of 38How web servers work (cont'd)
<html> <body> <h1>My index page</h1> <p>This is the content on the index page!</p>
</body></html>
Slide 15 of 38How web servers work (cont'd)
The browser then interprets the request, which is usually in HTML format, and renders the HTML on screen.
This is why the same HTML can look different between different browsers – for instance Firefox and Internet Explorer – because the rendering engines inside the browsers are different. This is a key source of frustration for web
developers!
Slide 16 of 38
How PHP works with the web server
Okay, so we've seen how HTTP requests and responses work. But this is exactly how HTML works! How does PHP come into it? Before the web server (for example Apache) issues
the response, the PHP interpreter is invoked and processes the information in the PHP script.
This is why PHP files are called 'filename.php' and normal (static) html files are called 'filename.html' – it helps the web server determine whether to invoke the PHP interpreter or not.
Slide 17 of 38
How PHP works with the web server (cont'd)
For example, let's say I put this code in a file;
<html> <body> <h1> <?php echo date("F j, Y, g:i a"); ?> </h1> </body></html>
… and I call the file 'something. html' What will be displayed on the page?
Slide 18 of 38
How PHP works with the web server (cont'd)
Rather than the current date and time, it will display something like this;
<?php echo date("F j, Y, g:i a"); ?>
This is because the PHP interpreter was not invoked due to the file being named something.html – the PHP script is not interpreted, and values substituted before the web server issued the response!
Slide 19 of 38
How PHP works with the web server (cont'd)
If on the other hand, the file was named something.php, the PHP interpreter would be invoked and you would see something similar to;
June 19, 2010, 2.30 pm This is because the PHP interpreter was
invoked, and the PHP script processed before the response was sent to the user agent.
Slide 20 of 38
Quick recap before we take a look at some code
PHP is a dynamic scripting language generally used with a web server
User agents (browsers) issue requests to web servers. Web servers process these requests. They may invoke the PHP interpreter. The web server then issues a response back to the user agent, usually in HTML. The user agent then renders the HTML, and that's why we see a web page :-)
Slide 21 of 38
PHP Basics:Variables
Examples of declaring variables in PHP<?php $myString = 'Hello world'; $myInt = 999; $myFloat = 12345; $myArray = array(); $myObject = new someObject();?>
Slide 22 of 38
PHP Basics:Variables
Variables in PHP don't have to be explicitly declared – but it is best practice to do so for readability and for debugging
Variables in PHP are loosely typed – the type of value is not stated when the variable is declared – it is implicit. This can also be difficult to debug – as variables can unknowingly be cast into different types – with unexpected results!
Slide 23 of 38
PHP Basics:Variables
Basic example. What might happen with $total being declared implicitly here?
<?php
$cost = 10; // declared explicitly
$units = 5; // declared explicitly
// do some stuff in here
$total = $cost * $units; // implicit
?>
Slide 24 of 38PHP Basics:
Control structures
Control structures alter the flow of execution of a PHP script.
if...then...else If something is true, do x, else do y
While... While something is true, keep doing x
Switch If the condition is a, do action for a
Slide 25 of 38
PHP Basics:Control structures
try...throw...catch Try to do something, but if the something fails, then
throw an error. The error can then be caught and processed, such as by displaying an appropriate error message
This is a more advanced control structure, but it is very worthwhile learning, particularly if you plan to use object oriented programming.
Slide 26 of 38
PHP Basics:Arrays
Arrays in PHP are incredibly powerful. There are a large number of array functions available to choose from.
Arrays in PHP are essentially collections of key-value pairs. In some programming languages, the key is always a number. In PHP, the key can be a string or a number. This is referred to as an associative array.
Slide 27 of 38
PHP Basics:Arrays
<?php $array1 = array(10, 20, 40, 80, 160); $array2 = array('banana', 'pear', 'apricot');
$array3 = array(0 => 4, 3 => 3838); $array4 = array('beans' => 'borlotti', 'icecream' => 'chocolate');
?>
my
Slide 28 of 38
PHP Basics:Working with forms
One of the common uses for PHP is to process web based forms. When a HTML form is submitted to a PHP script, a number of variables are made available to PHP.
To make a HTML form submit to a PHP script, the path to the PHP script has to be given in the FORM element;
<form name="myForm" action="/myscript.php/">
Slide 29 of 38
PHP Basics:Working with forms
Once the form has been submitted, the values will be available in $_POST superglobal array. We can iterate through this array to process the form, send emails etc.
<form name="myForm" action="/myscript.php/"> <input type=”text” name=”myTextField”></form>
Slide 30 of 38
PHP Basics:Working with forms
The data from this input field will be available in the variable;
$_POST['myTextField'] This data can then be used for instance to put
into an email, insert into a database etc.
Slide 31 of 38
PHP Basics:Working with databases
PHP can connect to a database using functions specific to the database
For example MySQL Database connection usually requires
username, password and database name Not enough time here to cover all database
concepts, but can cover a brief introduction to database theory if you'd like?
Slide 32 of 38
Commonly used free and open source software
which utilises PHP
Wordpress – blogging and content management softwarehttp://www.wordpress.org
Drupal – content management softwarehttp://www.drupal.org
PHPMyAdmin – provides an easy to use web interface to MySQL databases http://www.phpmyadmin.net
Slide 33 of 38
Commonly used free and open source software
which utilises PHP (cont'd)
Zen Cart – online shopping carthttp://www.zen-cart.com
Moodle – Learning Management Softwarehttp://www.moodle.org
Mahara – e-Portfolios http://www.mahara.org
Media Wiki – wiki softwarehttp://www.mediawiki.org
Slide 34 of 38PHP frameworks
A framework is basically a collection of components that make development easier by abstracting commonly used functions. The developer can then focus on the 'core features' of the application they are creating, rather than worrying about formatting, database connections etchttp://en.wikipedia.org/wiki/Comparison_of_web_application_frameworks#PHP_2
Examples include Zend, Symfony
Slide 35 of 38
More information and resources
What is PHP?http://au.php.net/manual/en/intro-whatis.php
What can PHP do?http://au.php.net/manual/en/intro-whatcando.php
Introductory tutorial (from PHP.net)http://au.php.net/manual/en/tutorial.php
Slide 36 of 38
More information and resources (cont'd)
Other good introductory tutorials(mostly from Slideshare) http://www.slideshare.net/cwarren/introduction-to-p
hp-for-wit2009 http://www.slideshare.net/alexjones89/an-introducti
on-to-php http://www.slideshare.net/binnyva/php-the-easiest-l
anguage-to-learn-presentation
Slide 37 of 38User groups
PHP Melbournehttp://phpmelb.org/irc://freenode/phpmelb
PHPWomen (XY welcome, we exist to be inclusive and help support women in learning and mastering PHP)http://www.phpwomen.orgirc://freenode/phpmelb@PHPWomen on Twitter
Slide 38 of 38
Related user groups and developer communities
Melbourne WordPress grouphttp://groups.google.com/group/wpubmelb
Melbourne Drupal grouphttp://groups.drupal.org/australia
Melbourne MySQL user grouphttp://lists.mysql.com/ug-melbourne?sub=1
