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PHP By Jonathan Foss
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Summary Dynamic vs Static pages Introduction to PHP PHP Syntax
PHP Objects PHP functions Security Session/Cookies More Information
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Static Websites Use HTML files (.html, .htm)
Content is created and uploaded to the web server via FTP Every user sees the same content Content remains the same until the author uploads a new version of the page Can include client-side scripting (such as Javascript)
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Dynamic Websites Generate HTML as each server request is made
Uses Common Gateway Interface to communicate extra variables between browser and server Several popular CGI languages PHP .php Perl .cgi, .pl Active Server Pages .asp More multi-purpose languages such as C/C++, Java Output HTML can be different for each user
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PHP Scripting language developed especially for the web
Scripts are interpreted by the server every time a client requests a page from the web server The output of the script can therefore depend on: Parameters set by the user Variables stored on the server External data sources such as databases or XML feeds Because scripts are executed on the server, the client never gets to see the actual PHP source code PHP originally stood for Personal Home Page
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Uses of PHP PHP usually used to output HTML code to the browser
PHP can also be used to generate other content such as XML, CSS or Javascript files With extra libraries it can also generate more complex binary files such as images, zips or PDFs Can also be used on the command line (without a web server), and is now popular for off-line scripting.
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Popular uses of PHP
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PHP Architecture Client Server Apache Web Browser PHP file MySQL PHP
This is often referred to as a LAMP (or WAMP) stack: Linux (or Windows) Apache MySQL PHP
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PHP Installation Binaries and source code available from: Or you can download the whole LAMP stack in one installation package: XAMPP Or EasyPHP (Windows only)
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PHP Syntax The PHP preprocessor only interprets code between tags <?php and ?> Any other content is output. Variables are defined using the $ symbol Statements must end with a ; To output text using php, use the command echo Strings can be concatenated with . character
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PHP Syntax Can use \ to escape special characters such as “
$myvar = 4; $text = “The value of the variable is “ ; echo $text . $myvar; $text = “The value of the variable is \”$myvar\””; echo $text; ?> Will output: The value of the variable is 4 The value of the variable is “4”
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First PHP Script: hello.php
<html> <head><title>Test PHP Program</title></head> <body> <?php echo “<p>Hello</p>”; ?> </body> </html> Note: this is a very basic PHP script, and generates the same code every time!
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Arrays in PHP Arrays (and variables) are assigned without declaration
Can be declared all at once: $myarray = array(1,3,5,7,9); Or can be assigned by index: $myarray[5] = 11; Can even use strings as indices: $myarray[“name”] = “test”; Arrays can hold any data type (including other arrays => multidimensional arrays)
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HTML Forms As you have seen in the HTML lecture, a simple HTML form might be: <form action=“hello.php” method=“GET”> <input type=“text” name=“name”> <input type=“submit” value=“submit”> </form> Assuming I type my name in the box When I click the submit button the browser changes the URL to: hello.php?name=Jonny This is because the GET method is used.
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Accessing CGI Variables
GET variables are accessible using $_GET So if the url says: hello.php?name=Jonny The name is accessible in $_GET[“name”] POST is similar to GET, except the data is sent in the body of the request rather than in the header (and is therefore hidden from the user). POST variables are stored in $_POST
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Environment Variables
Description $_GET Variables encoded on request header $_POST Variables sent in request body $_SERVER Variables about the server and PHP configuration $_FILES Stores contents of files uploaded by the client $_REQUEST Contains a combination of both $_GET and $_POST $_SESSION Temporary data stored within a particular browser session $_ENV Environment variables from the system $_COOKIE Variables stored in a cookie
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String Functions strlen($string); sub_str($string,$start, [$len]);
Returns the number of characters in $string sub_str($string,$start, [$len]); Returns a substring of $string, that starts at $start and is $len characters long explode($delim, $string); Returns an array of substrings between the delimiters md5($string); Returns an md5sum of $string (useful for storing passwords in a database)
![String Functions strlen($string); sub_str($string,$start, [$len]);](http://slideplayer.com./slide/7345811/24/images/17/String+Functions+strlen%28%24string%29%3B+sub_str%28%24string%2C%24start%2C+%5B%24len%5D%29%3B.jpg "Returns the number of characters in $string. sub_str($string,$start, [$len]); Returns a substring of $string, that starts at $start and is $len characters long. explode($delim, $string); Returns an array of substrings between the delimiters. md5($string); Returns an md5sum of $string (useful for storing passwords in a database)")
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PHP Conditional Statements
<?php $mark = 70; if($mark == 100) echo “You got them all right!”; if($mark >= 90){ echo “Passed: Grade A”; }elseif($mark >= 70){ echo “Passed: Grade B”; }else{ echo “Failed”; } ?>
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PHP Loops <?php $i = 0; while($i < 10){ echo “Number is $i”; $i++; } for($i = 0; $i < 10; $i++) ?> In this case, both loops are equivalent
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PHP Loops <?php $namestr = “Alexandra,Maurice,Fawaz,Jonny,Matthew”; $names = explode(“,”,$namestr); for($i = 0; $i < count($names); $i++) echo “Hello “ . $names[$i] . “\n”; foreach($names as $name) echo “Hello $name\n”; ?> In this case, both loops are equivalent
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Objects in PHP Variables are declared without a type
However, objects do exist in PHP class Square{ protected $size; public function __construct($size){ $this->size = $size; } public function getArea(){ return $size * $size;
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Objects in PHP - PHP5 Only
Can declare functions and variables Can have a constructor: __construct() Can have a destructor: __destruct() Can use public, protected, static and private keywords before variables/functions – these keywords work in the same way as they do in Java Use -> to access functions and variables (even from within the class)
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Procedural vs OOP PHP originally a procedural language
Object support introduced in PHP3 – completely rewritten in PHP5 Object type is determined when the variable is assigned <?php $var = “test”; $var = 42; $var = new Square(2); ?> $var is now a string $var is now an integer $var is now a square
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More PHP Commands isset()
Returns true if the variable has been set – useful for environment variables (such as isset($_GET[“name”])) phpinfo() Generates an html page describing the php setup – good for discovering what libraries are installed include() Includes another php script (see also require()) fopen(), fread(), fclose() Used for reading local files (on the same server) system() Execute shell commands on the server header() Sets header parameters of HTTP response, for example header(“Location: index.php”); Which would redirect the user to index.php CURL Implements HTTP to get web resources from other sites libxml Library for XML functions (see also SimpleXML)
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Other types of output Although PHP files usually output HTML, PHP can output other files To do this, the appropriate header must be sent – for instance to output an xml feed: header("Content-type: text/xml"); Other uses might be to create a dynamic CSS file, or create a picture using the GD library.
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Sessions and Cookies Sessions maintain a unique string as the user navigates between pages, this string references a file stored on the server, which can contain variables Sessions are lost when the browser is closed Cookies store text files on the client side and are therefore persistent between browser sessions Sessions Cookies session_start() $_SESSION[“views”] = 1; echo “You’ve visited “; echo $_SESSION[“views”] . “times”; setcookie(“views”,1,$expirydate) echo $_COOKIE[“views”] . “times”;
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More Information http://www.php.net http://www.tizag.com/phpT/
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Assignment Write a guest book application for your website
Find some PHP hosting (google free php hosting) Write an HTML form to accept user input (name, comments, address, etc.) Implement a way of interpreting the responses, and storing them Make sure there’s a way I can actually see your PHP code Deadline: Thursday 26th March 2009
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Summary Dynamic vs Static pages Introduction to PHP Uses of PHP
PHP Syntax PHP Objects PHP functions Security Session/Cookies More Information
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Thank You Any Questions?
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