Introduction to PHPAhmad Karawash

2015

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ObjectivesTo understand what PHP is and how a PHP script works with a Web

Browser and a Web ServerTo learn what software and components

you need to get started with PHPTo create and run a simple PHP script

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Client–Server model

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The client–server model of computing is a distributed application structure that partitions tasks between the providers of a service, called servers, and service requesters, called clients.

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Client-Side ScriptingClient scripts are interpreted by the web

browserFor example: JavaScriptClient scripts can:

Alter the appearance of the document Validate form fields Perform general computational tasks

Client scripts can be embedded or attached

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Server-Side ScriptingServer scripts are interpreted by the web

serverCommon languages are

PHPASP JSP Perl

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What is PHP?PHP is a computer scripting languageDeveloped by Rasmus Lerdorf from the Apache GroupAppeared in 1995Originally designed for producing dynamic web pagesRuns on most operating systems and platformsURL: http://www.php.net

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What is PHP?Advantages of Using PHP to enhance

Web pages: Easy to use. Open source. Works on Multiple platforms.

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How PHP Pages are Accessed andInterpreted

Web browser

3. Receive request find file and read it

4. Execute PHP statement

5. Send results back

Web Server1. Enter name

Submit cancel

7. Result

Web browser

This is your phone nb: xxx

2. Send request

6. Receive

request

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How PHP Pages are Accessedand InterpretedHow do Web Servers work?

Client specifies document at a specific web address that is desired (specified by a URL) Ex: http://www.MUM.com

If the document is html or text, the server simply forwards it back to the clientIt is then rendered in the client's browser

However, if it has embedded PHP, the server first executes the PHP, replacing the PHP code with its output in the document

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How PHP Pages are Accessedand InterpretedThe modified document is then sent back to

the clientNote that the client never sees the PHP code

This is important – typically client should not see logic / code that server executes to process requests

The server may be accessing files whose names should not be seen by the client

The only reason the client even knows PHP is involved is due to the file extension : .php

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Getting Started with PHPTo develop and publish PHP scripts all

what you need is:A Web server with PHP built into itA client machine with a basic text editor

and Internet connectionFTP or Telnet software

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Exploring the Basic PHPDevelopment ProcessThe basic steps you can use to develop and

publish PHP pages are:1. Create a PHP script file and save it to a

local disk.2. Use FTP to copy the PHP file to the server.3. Access your file using a browser.

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Creating a PHP Script File andSaving It to a Local DiskYou can use a number of different

editors to create your PHP script files.The PHP script starts with a <?php tag

and ends with ?>.Between these tags there is a single PHP

print statement.

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Accessing Your File Using aBrowser

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SyntaxIf you have a syntax error then you have

written one or more PHP statements that are grammatically incorrect in the PHP language.

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If Use Improper SyntaxSuppose you use the wrong syntax:For example error with quotation mark1. <?php2.3. print ( “Hello World !);4. ?>

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A Little About PHP's SyntaxSome PHP Syntax Issues:

Be careful to use quotation marks, parentheses, and brackets in pairs.

Most PHP commands end with a semicolon (;).

Be careful of letter case.PHP ignores blank spaces.

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Embedding PHP StatementsWithin HTML DocumentsOne way to use PHP is to embed PHP scripts

within HTML tags in an HTML document.1. <html>2. <head>3. <title>HTML With PHP Embedded</title> </head>4. <body>5. <font size=5 color=”green”>Welcome To My

Page</font>6. <?php7. print ("<br> Using PHP is not hard<br>");8. ?>9. and you can learn to use it quickly!10. </body></html>

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Would Output The Following ...

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VariablesVariables in PHP are represented by a dollar

signPHP supports eight types:

boolean, integer, float, double, array, object, resource and NULL

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Variables example<?php

$x=“Hello”;Print($x);

?>

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Using Comments withPHP ScriptsComments enable you to include

descriptive text along with the PHP script.

Comment Syntax - Use //<?php// This is a comment?>

Can place on Same line as a statement:<?phpprint ("A simple initial script"); //Output a line?>

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Example Script with Comments1. <html> <head>2. <title> page title</title> </head>3. <body> <h1> Comment example PHP</h1>4. <?php5. //6. // Example script to output HTML tags7. //8. print (“In PHP you can use: <i>Comments</i>");9. print ("</body></html>");10. ?>

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Alternative Comment SyntaxMultiple line comments.

<?php/*A script that gets information about thePHP version being used.*/?>

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SummaryYou can embed a PHP script within an HTML

document or run it as a stand-alone script.

To begin working with PHP you need a Web server with built-in PHP, a client machine with a basic text editor, and FTP or Telnet software.

PHP script process: write the PHP script, copy its file to the Web server, and access the file with a Web browser.

Comments can be proceeded with two forward slashes (//) or (/* … */).

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Simple HTTP Request

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HTTP With JavaScript

The client browser parses the HTML file, finds the script and executes it locally

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HTTP on Demand1. Web server loadsthe script from itsfile system

2. Web serverpasses the scriptto the interpreter

3. The interpreterruns the script andpasses its output tothe web server

4. The web serverblindly passes theoutput to the client

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Data-driven HTTP Request

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Three-tiered Web Site

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ClientUser-agent: Firefox

ServerApache HTTP Server

example requestGET / HTTP/1.1Host: www.tamk.fiUser-Agent: Mozilla/5.0 (Mac..)...

response

DatabaseMySQL

PHPPHP