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269200 Web Programming Language

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269200
Web Programming Language
Week 6
Dr. Ken Cosh
PHP Functions & Objects
Recap
• Introducing PHP
•
•
•
•
•
Server Side Scripting
Variables
Flow Control
Operators, Conditionals
Form Handling
This Week
• Extending PHP
•
•
Functions
Objects
Why Functions?
• Less Typing
• Less Syntax
• Less Errors
• Quicker loading time
• Quicker Execution time
• Simplify Logic
Existing Functions
• PHP has hundreds of functions…
•
•
•
•
echo strrev(“.dlrow olleH”);
echo str_repeat(“Hip “, 2);
echo strtoupper(“hooray!”);
echo ucfirst(“ken”);
• You will gradually pick up more functions as you face more challenges…
Defining Functions
function function_name(parameter, parameter)
{
//Statements
}
Returning Values
• You can return variables
•
return $n1;
• You can return an array of values
•
return array($n1, $n2, $n3);
Reference Parameters
•
You can prefix a variable with & to make it a reference variable
•
•
i.e. passes a reference to the value, rather than the variable itself.
This allows your function to directly modify the variable’s value.
function fix_names(&$n1, &$n2)
{
$n1 = ucfirst(strtolower($n1));
$n2 = ucfirst(strtolower($n2));
}
Where to function?
• You could write functions anywhere within your PHP files
• Overtime you are likely to create a lot of functions, so you could create a file
of functions
•
functions.php
• You can then include that file in your page
include “functions.php”;
include & require
• include will attempt to include another file
•
if the file doesn’t exist it will produce a warning
• require is the same, except if the file can’t be found it will produce a fatal
error
require “function.php”
include_once, require_once
• You may end up with multiple files including multiple other files.
• If file A includes file B and file C, and file B include file C, you could run into
naming problems…
•
include_once and require_once will fix it.
function_exists
• PHP is continually developed, there are multiple versions.
• We may need to check if a function exists in our version
if(function_exists(“array_combine”)) { …}
•
array_combine() is specific to PHP5
• Think! How might needing to do this change between php and javascript?
Objects in PHP
•
We can define classes in PHP
class User
{
public $name, $password;
function f1()
{
//Code Here
}
}
Notice, no semicolon!
Objects in PHP
• We can create instances of our class;
$object = new User;
Notice, no $
$object->name = “Ken”;
$object->password = “secret”;
print_r($object);
Cloning an Object
•
What would happen here?
$object1 = new User;
$object1->name = “Ken”;
$object2 = $object1;
$object2->name = “Jeff”;
echo “object 1 name = “ . $object1->name . “<br>”;
echo “object 2 name = “ . $object2->name;
Cloning an Object
•
An Alternative
$object1 = new User;
$object1->name = “Ken”;
$object2 = clone $object1;
$object2->name = “Jeff”;
echo “object 1 name = “ . $object1->name . “<br>”;
echo “object 2 name = “ . $object2->name;
Constructors
•
You could use the same name as the class (User), or, you could use __construct()
class User
{
function __construct()
{
$username = “Guest”;
}
public $username;
}
Destructors
•
We can also have destructor methods;
class User
{
function __destruct()
{
//Code
}
}
Public, Protected, Private
• Of course, properties and methods can be public, protected or private in
PHP;
•
•
•
public – accessible anywhere
protected – accessible from within the class, or subclasses
private – only accessible from within the class
Inheritance
• Without wanting to go into details, PHP also supports inheritance
class Subscriber extends User
{
}
Exercise – Calendar Part I
• Create a form for submitting appointments to a calendar.
• The form should allow users to input the following information:•
•
•
Title
Date
Details
• Once the user submits the form, the ‘event’ should be displayed on a
calendar on a new page.
Exercise - Example
1
Title
Date
Detail
FoE Mtg
13/12/2011
ASEAN-QA meeting, review
the handbook first.
Submit 2
Exercise - Example
2
December 2011
Foe Mtg in 1 day(s)
3
Exercise Example
3
Appointment Detail
Title
Date
Detail
FoE Mtg
13/1/2013
ASEAN-QA meeting, review
the handbook first.
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