PHP Hypertext Preprocessor

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PHP- Hypertext Preprocessor

• COSC 418
• Design of Multiplayer Games
• K. Harmeyer

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Scripting

• Programming basics but a scripting language
• Code interpreted, not pre-compiled
• Client-side scripting Scripts processed by web
  browser Typically JavaScript
• Server-side scripting Scripts evaluated and
  processed by script engine Includes Perl, JSP,
  CFM, ASP, and PHP

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PHP Hypertext Preprocessor

• A recursive name!
• An interpreted language
• A scripting language
• Syntax similar to C and Perl
• Used to develop server-side scripts
• Complete, standalone scripts
• Scripted elements embedded in HTML
• Tightly integrated with Apache and MySQL

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PHP Hypertext Preprocessor

• Identified by special characters lt?php ?gt
• Characters offset or escape code from HTML
• Contents evaluated as PHP code
• All code must be in form of Expressions
  Functions Conditions Loops

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Basic HTTP Conversation
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HTTP Conversation with Script Execution
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Scripting with PHP

• Simple expressions with comments
• // store the value 6 into a variable named
  amountamount 6
• // store the value Maggie into a variable named
  namename Maggie
• /add 4 to the value stored in amount and store
  the result in a variable named total. Notice the
  multi-line comment/total 4 amount

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What is It?

• PHP pages are normal HTML pages with PHP commands
  inserted into them.
• The Web server preprocesses the page and converts
  the page to HTML then sends it to the browser.

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Sample hello.php

• lthtmlgt ltheadgt  lttitlegtPHP Testlt/titlegt
  lt/headgt ltbodygt  lt?php echo 'ltpgtHello
  Worldlt/pgt' ?gt lt/bodygt
• lt/htmlgt
• The file is parsed by PHP and sent to the browser.

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HTML Delivered to Browser

• lthtmlgt
• ltheadgt
• lttitlegtPHP Testlt/titlegt
• lt/headgt
• ltbodygt
• ltpgtHello Worldlt/pgt
• lt/bodygt
• lt/htmlgt

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What Does it Do?

• Serverside scripting
• Dynamic Web content
• Connects with server files, text and MySQL
• Generates HTML documents on the fly
• Your COSC 418 Web pages
• Command line scripting
• Manage server tasks from the command line
• Client-side GUI applications
• PHP-GTK

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We Care Because

• Wide ranging support for databases
• http//ccbc-elnx.ccbcmd.edu/kharmeyer/plpsites.ph
  p
• Easy additions/deletions
• Template use for similar pages
• http//iat.ubalt.edu/courses/cosc418.001_sp07
• Easy updates

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Origins of PHP

• Rasmus Lerdorf
• Concept -1994
• PHP 1.0 1995 Personal Home Page tools
• Open Source
• Current version PHP 5.2.1 release 2/14/2007
• Now runs on Apache, Microsoft IIS and Netscape
  servers.
• Free!
• www.php.net

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What Do You Need?

• Apache Server Version 2.2.6
• www.apache.org
• PHP Version 5.2.4
• www.php.net
• MySQL Version 4.1
• http//dev.mysql.com/downloads/mysql/4.1.html

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index.php

• lt!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01
  Transitional//EN"gt
• lthtmlgt
• ltheadgt
• lttitlegtCOSC 418 Welcome Pagelt/titlegt
• ltlink rel"stylesheet" type"text/css"
  href"project.css"gt
• lt/headgt
• ltbody bgcolor"ffffff"gt
• ltcentergt
• lttable width"800" cellpadding5gt
• lt?php include ("titles.html") ?gt
• lttrgt
• lttd valign"top" bgcolor"70b8c9"gt lt?php
  include("menu.html") ?gt lt/tdgt
• lttdgt ltp align"right"gtltspan
  id"subhead"gtMondays, 200 -430
• pm ltbrgt
• Academic Center 219
• lt/spangtlt/pgt
• ltp align"left"gtltspan
  id"paragraph"gtThis is the home page for the
  Design
• of Multiplayer Games course. Watch
  this space for late-breaking news
• about the course. Use the menu at the
  left to access course materials.lt/spangtlt/pgt

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Page Counter for Webpage Access

• What would we need?

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Page Counter for Webpage Access

• Need a text file on server with count in it.
• Need PHP code in Web page to
• Access current count in text file on server
• Get current count
• Increment the count
• Save text file with updated count on server.

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PHP Script

• counterScript.php
• lt?php
• // Page access counter include script in page
  to be counted
• // EDIT KMH 5/20/2001
• // initialize variables ensure there is a file
  named counter.txt on the server in same folder
• TextFile "counter.txt"
• Counter trim(file_get_contents(TextFile))
• // Access current count in text file on server
• FilePointer fopen(TextFile, "r")
• // Get current count
• Counterfgets(FilePointer, 1024)
• fclose (FilePointer)
• // Increment the count
• settype(Counter, "integer")
• Counter

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PHP file to Activate Counter

• counter.php
• lt!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01
  Transitional//EN"gt
• lthtmlgt
• ltheadgtlttitlegtPage Counterlt/titlegtlt/headgt
• ltbodygt
• The number of hits for this page is lt?php include
  (counterScript.php) ?gt
• lt/bodygt
• lt/htmlgt
• In Class Activity
• Add this counter to your cosc418 index page.

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High Scores List

• Think about an algorithm for managing a high
  scores list for a PHP game.
• Write the steps you would need to program to
  accommodate a high scores feature.
• Bring the algorithm to class next week.

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How to Get Started

• Read Chapter 2 Language Basics
• Note how the syntax is similar to C
• Note what is different
• Look at course site.
• Selected PHP source files are available for view
  in PHPsource sub folder.
• Download and install free Apache/PHP/MySQL
• Edit your homework pages
• Create a Look and put it in a titles.html file
• Include that file in each of your homework pages.
• lt?php include(titles.html") ?gt