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 How to use include and require functions and scope HTTP, CSS, Javascript What does it all mean??? Debugging it all
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
Why use PHP? Available nearly everywhere Very good support/documentation Plenty of tools to help Fast development Even has a GUI library!
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
Heredoc/Nowdoc echo <<<AnYtHiNg This expands $variables and \n newlines AnYtHiNg; echo <<<'anything' This doesn't expand $variables or \n newlines anything;
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 }
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";
$_REQUEST $_REQUEST is equivalent to: array_merge($_get, $_POST, $_COOKIES); Order can be arranged in the php.ini file
DON'T USE EXTRACT ON USER INPUT! (use $_REQUEST instead) Example
Quicker file handling $file_contents_as_string = file_get_contents($filename) file_put_contents($filename, $contents_to_write)
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'];
Includes/Requires file.php: $var = "Hello World!"; page.php: $var = "Goodbye World!"; include("file.php"); echo $var; Outputs: Hello World!
Variable Scope In Java: String s = "Hi"; if(true){ System.out.println(s); } System.out.println(s); This works fine
Variable Scope (cont.) In Java: if(true){ String a = "Hello World"; } System.out.println(a); Compile error!
Variable Scope (cont.) In PHP: $string = "Hi"; if(true){ echo $string; } Outputs: Hi
Variable Scope (cont.) In PHP: if(true){ $string = "Hi"; } echo $string; Outputs: Hi (not a syntax error!)
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!
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!"
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
Functions (cont.) In PHP: function myfunction($one, $two = "default"){ //do something; }
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
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
HTTP (cont.) Sample HTTP Response HTTP/1.1 200 OK Date: Mon, 07 Mar 2011 21:05:05 GMT Content-Type: text/html Content-Length: x <html>...</html> Example in BurpSuite
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>
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; }
CSS (cont.) Syntax: <selector> { <property>:<value>; }
Javascript Client Side Scripting Server forms the html Javascript manipulates that html AJAX used to communicate Install JQuery, and use it
PHP + HTTP + CSS + Javascript
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
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