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Intro to Web Programming

Intro to Web Programming. using PHP, HTTP, CSS, and Javascript Layton Smith CSE 4000. Intro. Types in PHP Advanced String Manipulation The foreach construct $_REQUEST environmental variable Correction on extract and ereg Easier file access The session

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Intro to Web Programming

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  1. Intro to Web Programming using PHP, HTTP, CSS, and Javascript Layton Smith CSE 4000

  2. Intro • Types in PHP • Advanced String Manipulation • The foreach construct • $_REQUEST environmental variable • Correction on extract and ereg • Easier file access • The session • How to use include and require • functions and scope • HTTP, CSS, Javascript • What does it all mean??? • Debugging it all

  3. Types in PHP Variable Types     int, float, bool, string     array     object     resource     null Comparisons with ==, !=, ===, !== 1 == "1" is true 1 === "1" is false 1 === 1 is true

  4. Why use PHP? • Available nearly everywhere • Very good support/documentation • Plenty of tools to help • Fast development • Even has a GUI library!

  5. Advanced Strings • Dot (.) is concatenation (not de-reference) $string = "Hello World"; echo 'This is a \n $string'; echo "This is a \n $string"; Outputs: This is a \n $string This is a Hello World

  6. Heredoc/Nowdoc echo <<<AnYtHiNg This expands $variables and \n newlines AnYtHiNg; echo <<<'aNyThInG' This doesn't expand $variables or \n newlines aNyThInG;

  7. Array Handling In Java: Iterable<Clazz> i = new Iterable<Clazz>(); //... for(Clazz c : i){     //i gets looped through and assigned to c at each loop } In PHP $array = array("key1" => "value1", "key2" => "value2"); foreach($array as $key => $value){     //$key is the index/key, and $value is the value }

  8. Array Handling cont. Array constructor: $array = array("item", "key1" => 1, "key2" => "value"); $array[] = "value1"; $array[] = "value2"; //equivalent to $array = array("value1", "value2"); //or $array[0] = "value1"; $array[1] = "value2";

  9. $_REQUEST $_REQUEST is equivalent to: array_merge($_GET, $_POST, $_COOKIES); Order can be arranged in the php.ini file

  10. DON'T USE EXTRACT ON USER INPUT! (use $_REQUEST instead) Example

  11. Quicker file handling $file_contents_as_string = file_get_contents($filename) file_put_contents($filename, $contents_to_write)

  12. The Session session_start() sends user PHPSESSID cookie.  $_SESSION holds only this user's data First script: $_SESSION['key'] = $value; Second script: $value = $_SESSION['key'];

  13. Includes/Requires file.php: $var = "Hello World!"; page.php: $var = "Goodbye World!"; include("file.php"); echo $var; Outputs: Hello World!

  14. Variable Scope In Java: String s = "Hi"; if(true){     System.out.println(s); } System.out.println(s); This works fine

  15. Variable Scope (cont.) In Java: if(true){     String a = "Hello World"; } System.out.println(a); Compile error!

  16. Variable Scope (cont.) In PHP: $string = "Hi"; if(true){     echo $string; } Outputs: Hi

  17. Variable Scope (cont.) In PHP: if(true){     $string = "Hi"; } echo $string; Outputs: Hi (not a syntax error!)

  18. Variable Scope (cont.) Two scopes:     Global Scope - all variables outside of a function     Function Scope - only variables declared in function $a = "Hi!"; function f(){     echo isset($a)?"It is set!":"It is not set!"; } f(); Outputs: It is not set!

  19. Variable Scope (cont.) Superglobals:     $_GET, $_POST, $_SESSION, etc... always in scope. Use the global keyword $a = "Hi!"; function f(){     global $a;     echo isset($a)?"It is set!":"It is not set!"; } f(); Outputs: "It is set!"

  20. Functions In Java: class myClass{     int myFunction(int one, String two){          //do stuff     }     int myFunction(int one){          return myFunction(one, "default");     } } Perfectly legitimate Java code

  21. Functions (cont.) In PHP: function myFunction($one, $two = "default"){     //do something; }

  22. Functions (cont.) In Java: class myClass{     int myFunction(int one, boolean two){ return something; }     int myFunction(boolean two, int one){ return something; } }  No equivalent in PHP

  23. HTTP Sample HTTP request POST /index.php HTTP/1.1 Host: example.com Content-Type: application/x-www-form-urlencoded key1=value1&key2=value%20of%20key2

  24. HTTP (cont.) Sample HTTP Response HTTP/1.1 200 OKDate: Mon, 07 Mar 2011 21:05:05 GMTContent-Type: text/html  Content-Length: x <html>...</html> Example in BurpSuite

  25. CSS Cascading Style Sheets Order of priority: 3. <link href="special.css" rel="stylesheet" type="text/css" />2. <style type="text/css">    ...</style>  1. <div style='background-color: red;'></div>

  26. CSS (cont.) Selectors: E - element E #id - element with id='id' .class - element with class='class' E > F - element F that is child of E E F - element F that is descendant of E div.red {     color: red; }

  27. CSS (cont.) Syntax: <selector> {     <property>:<value>; }

  28. Javascript • Client Side Scripting • Server forms the html • Javascript manipulates that html • AJAX used to communicate • Install JQuery, and use it

  29. PHP + HTTP + CSS + Javascript

  30. Debugging everything • Use Firebug/Chrome Developer Tools • See all parts of the HTTP transaction • Debug Javascript • Edit HTML realtime • Watch GET/POST requests live • Example

  31. Sources • php.net - PHPs equivalent to Java API • w3schools.com - Javascript/CSS/HTML reference • jQuery.com - Javascript wrapper library • portswigger.net/burp/ - BurpSuite •  http://getfirebug.com/ - Firebug for Firefox

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