Further Php

Objects and Classes Functions Global Arrays Passing Variables

An object is a self-contained set of related variables and functions Objects are defined using the class keyword A class is the template for an object Variables contained within a class are called class variables Class variables may have different scopes public : May be accessed directly private : May only be accessed within the class static : Only initialised once protected , global etc.

Class variables are referenced from outside the class using the -> $myClass->var = 4 Class variables are referenced from inside the class using $this-> $this->var = 4 $this must be used for private variables

You should have a constructor function which is called to create an instance of the class (an object) public function __construct([any arguments]){}

<?php class student{ public $sID; //Show the id to everyone private $sName; //Limit the name public function __construct ($name, $id) { $this->$sID = $id; $this->sName = $sName; } public function printStudent() { echo “Student ID: $this->sID <br /> Student Name: $this->sName”;} } $ student1 = new student(‘1234’, ‘Peter’) ; $ student1 -> printStudent (); ?>

Functions are a self-contained set of expressions and variables They are used to make a set of procedures repeatable function funcName($arg1, $arg2 [=default value]) A function can take arguments These arguments can have default values Values which are assumed if no value is provided

<?php function repeat($fname,$num=10) { echo "<ol>"; for ($i = 1; $i <= $num; $i++) echo "<li> $fname </li>"; echo "</ol>"; } echo "My name is "; repeat("Kai Jim",5); echo "My name is "; repeat(”Jim Kai"); ?>

<?php function buildRows($array){ $rows = '<tr><td bgcolor="blue">’ .implode('</td></tr><tr><td bgcolor="yellow">', $array) .'</td></tr>'; return $rows; } function buildTable($rows){ $table = "<table cellpadding='3’ border='2'> $rows </table>"; return $table; } $myarray = array('php tutorial','mysql tutorial','apache tutorial','java tutorial','xml tutorial'); $rows = buildRows($myarray); $table = buildTable($rows); echo $table; ?> Implode(glue, $array): Used to join array elements with a string

PHP creates 6 global arrays that contain EGPCS (Environment, Get, Post, Cookies and Server) information and File information PHP also creates an array called $_REQUEST[] that contains the unsafe variables. It’s content is dependant on configuration, but normally it contians the $_GET[], $_POST[] and $_COOKIES[] array variables amalgomated into one array.

$_SERVER – Information about the server session and the HTTP connection with the client. e.g. $_SERVER[‘ HTTPS ’] : Is a secure connection being used $_POST[] – All variables received as an inline posted data set, normally through using the POST method in an HTML form. e .g. $_POST[‘username’] $_GET[] – The values of any variables sent via the URL e .g. $_GET[‘username’]

$ _FILES – References to all files received, most commonly from HTML forms, using the POST method. $_ENV[] – Contains the values of any environment variables, such as the browser version e .g. $_ENV[‘HTTP_USER_AGENT’] $_COOKIES – Contains any cookies submitted as name value pairs $_SESSION – If PHP is being used for session management, this array is to store any session variables that need to be stored on the server between calls from the client.

$GLOBALS – Contains all the variables that are of global scope G lobal scope is a variable which is defined outside of any particular function They may also be referenced using the global keyword G lobal variables take precedence over locally defined variables

$a = 40; f unction add(){ $a = 30; $b = 20; global $a; return $a + $b; } echo “Going to add. Answer to 30+20 = ”.add(); $GLOBALS[] and global may both be used to access global variables $GLOBALS[] requires you assign the variable to a local variable Same as: $a = $GLOBALS[‘a’]

Where does the information which is submitted in a form go? <html> <body> <form action="welcome.php" method="post"> Name: <input type="text" name="name" /> Age: <input type="text" name="age" /> <input type="submit" /> </form> </body> </html> The information goes to the location specified by action=“”

The method used is post, so all variables sent are in the $_POST[] array <html> <body> Welcome <?php echo $_POST["name"]; ?>.<br /> You are <?php echo $_POST["age"]; ?> years old. </body> </html> The output will be Welcome James . You are 10 years old.

PHP creates a variable called within the SERVER global array called $_SERVER[‘PHP_SELF’] that contains the name of the current script/page (relative to the doc root) This is useful in creating forms This allows one page to handle all the form creation and handling May also make use of the isset() built-in PHP function Checks to see if a variable has been assigned a value

<?php if (!$_POST["surname"] or !$_POST["address"]){ ?> <form method="post" action="<?php echo $_SERVER['PHP_SELF'];?>"> <p>Your surname: <input type="text" name="surname"></p> <p>Your address: <input type="text" name="address"></p> <input button type="submit" value= "Please send me the brochure."> </form> <?php } else{ $sn = $_REQUEST['surname']; echo "<p>Thank you, $sn.</p>"; $addr = $_REQUEST['address']; echo "<p> We will write to you at $addr .</p>"; } ?>

<form method="post" action="<?php echo $_SERVER['PHP_SELF'];?>"> Select the programming languages you can use<br> <input name="language[]" type="checkbox" id="language[]" value="C++"> C++ <br> <input name="language[]" type="checkbox" id="language[]" value="Java"> Java <br> <input name="language[]" type="checkbox" id="language[]" value="PHP"> PHP <br> <input name="language[]" type="checkbox" id="language[]" value="ASP"> ASP <br> <input name="language[]" type="checkbox" id="language[]" value="Delphi"> Delphi <br> <input name="lang" button type="submit" value="Send it!"> </form> <?php if(isset($_POST['lang'])){ $language = $_POST['language']; $n = count($language); $i = 0; echo "The languages you selected are " . "<ol>"; while ($i < $n){ echo "<li>$language[$i]</li> "; $i++; } echo "</ol>"; } ?>

Steven M. Schafer (2005), HTML, CSS, JavaScript, Perl, and PHP Programmer's Reference , Hungry Minds Inc,U.S. Christopher Schmitt (2003), Designing CSS Web Pages, New Riders Larry Ullman (2005), PHP and Mysql for Dynamic Web Sites, Peachpitt Press The main site for all PHP information: http://php.net

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