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Intro to Web Programming
using PHP, HTTP, CSS, and Javascript
Layton SmithCSE 4000
Intro
Types in PHPAdvanced String ManipulationThe foreach construct$_REQUEST environmental variableCorrection on extract and eregEasier file accessThe sessionHow to use include and requirefunctions and scopeHTTP, CSS, JavascriptWhat does it all mean???Debugging it all
Types in PHPVariable Types int, float, bool, string array object resource null Comparisons with ==, !=, ===, !== 1 == "1" is true1 === "1" is false1 === 1 is true
Why use PHP?
Available nearly everywhereVery good support/documentationPlenty of tools to helpFast developmentEven 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 aHello World
Heredoc/Nowdoc
echo <<<AnYtHiNgThis expands $variables and \n newlinesAnYtHiNg;
echo <<<'aNyThInG'This doesn't expand $variables or \n newlinesaNyThInG;
Array Handling
In Java:Iterable<Clazz> i = new Iterable<Clazz>();//...for(Clazz c : i){ //i gets looped through and assigned to c at each loop}
In PHP$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/1.1Host: example.com Content-Type: application/x-www-form-urlencoded
key1=value1&key2=value%20of%20key2
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
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 EE F - element F that is descendant of E
div.red { color: red;}
CSS (cont.)
Syntax:
<selector> { <property>:<value>;}
Javascript
Client Side ScriptingServer forms the htmlJavascript manipulates that htmlAJAX used to communicateInstall JQuery, and use it
PHP + HTTP + CSS + Javascript
Debugging everything
Use Firebug/Chrome Developer ToolsSee all parts of the HTTP transactionDebug JavascriptEdit HTML realtimeWatch GET/POST requests liveExample
Sources
php.net - PHPs equivalent to Java APIw3schools.com - Javascript/CSS/HTML referencejQuery.com - Javascript wrapper libraryportswigger.net/burp/ - BurpSuite http://getfirebug.com/ - Firebug for Firefox
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