Web Programming

Introduction to PHP

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Objectives

• To understand what PHP is and how a PHP script works with a Web Browser and a Web Server

• To learn what software and components you need to get started with PHP

• To create and run a simple PHP script

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Web servers

• Can be considered at two levels:1. The physical computer that stores web files and web application

programs.2. More precisely, the web server is a specialized piece of software,

running on the server computer, which• receives requests, via the Internet, for web pages or programs• retrieves the pages / executes the programs• returns the results over the Internet to the browser.

• Common web servers:– Apache– Microsoft Internet Information Services (IIS)

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Web Application Program

• Carries out many dynamic tasks, such as the following: – Input a search term, search the WWW, and

return the results– Calculate and display the number of times that a

page has been viewed– Verify the input fields on a Web form– Save a Web form into a database– Display a special graph, or return the results of a

calculation based on data input from a form

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What is PHP?

• Original of PHP (Rasmus Lerdorf) [born in Qeqertarsuaq, Greenland]

• Server side – e.g. form handling, database access– (as opposed to Javascript which is

mainly clientside)• (X)HTML-embedded scripting language

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Basic Browser Web Server interaction

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1. Browser in Client sents http request e.g. http://localhost/~labuser/test.php

2. Server receives request and activates php to interpret php program (test.php)

3. Server sends html output to browser in client for display

PHP Advantages

Advantages of Using PHP to enhance Web pages:

– Easy to use.– Open source.– Multiple platform.

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Browser PHP MySQL Interaction

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A third layer can be added if php makes a call to a database to supply data in response to web browser request

Browser/PHP/database example

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Browser holds html form

Enter Details of Car

Reg Num

Make

Submit

PHP program- Receives values- Plugs them into database

query- Sends Request to database- Receives data and - Returns result as web page

Details of Car

Taxed ? YesMOT? YesReg Date: 1st Jan 2010

https://www.gov.uk/check-vehicle-tax

Car Database

PHP & Javascript

• Javascript– Client side– Good for form validation– Good for web page presentation– Poor for security– Some database access

• PHP– Server side– Better security– Good database access

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Getting Started with PHP

To develop and publish PHP scripts all you need is:

– A Web server with PHP built into it– A client machine with a basic text editor and Internet

connection– FTP software (if webserver used) Use localhost in the development phase and then

upload to the server

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Installation of Apache, PHP and MySQL

• In the lab: Apache server, PHP, MySQL installed

• At home: – Install Apache, PHP and MySQL separately, – Or install Apache, PHP, MySQL together using a

package, eg. WAMP or MAMP (for Windows or Mac)

– XAMPP installs very easily & is cross-platform (Windows or Mac)

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Install Apache, PHP & MySQL• Download XAMPP

http://sourceforge.net/projects/xampp

Installs Apache/PHP/MySQL (plus PERL)

Cross platform (Mac/Windows/Linux)

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Using Apache, PHP and MySQL• iMAC Lab

– Save your HTML file (e.g. test.html) or PHP file (e.g. myprog.php) under: Macintosh ID/Users/Labuser/Sites

– Run html or php file under Apache using: e.g. http://localhost/~labuser/test.html OR create subdirectory starting with b (e.g. student number

b00XXXXXX ) http://localhost/~labuser/b00XXXXXXClick on file in browser window

• Windows Lab/ Own Windows Machine[ Put files in C://xampp/htdocs e.g. hello.php URL to run file http://localhost/hello.php OR create subdirectory and click on browser list]

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Using MySQL

– http://localhost/phpMyAdmin MAC Lab Login (MySQL)

Login: labuser Password: macimd15

Windows Lab login (MySQL)Login: labuserPassword: Labuser1

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Creating a PHP Script File

You can use a number of different editors to create your PHP script files.

• TextWrangler (can add line numbers)• Save file with .php extension

[In Windows Lab can use Notepad++ to create PHP scripts]

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Working with HTML

• Use tags <?php // opening php tag

?> // closing php tag

Save the file with .php extension

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Accessing Your File Using a Browser

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You should use this URL in the iMac LAB:

• for html files: http://localhost/~labuser/page1.html

• for php files: http://localhost/~labuser/ex1.php

Print Statement Syntax

• The print statement syntax:

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print ( "Your message to print" );

Enclose messagein quotation

marks

Message to Output

End in asemi-colon

Parenthesis areoptional

Echo Statement Syntax

• The echo statement syntax:

echo "the message to print";

Echo almost identical to print

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If Use Improper Syntax

• Suppose you use the wrong syntax: 1. <?php2. print "A simple initial script;

3. ?>

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Missing inverted commas

A Little About PHP's Syntax

• Some PHP Syntax Issues: – Be careful to use quotation marks, parentheses, and brackets in

pairs. – Most PHP commands end with a semicolon (;).– Be careful of case.

– PHP ignores blank spaces.

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Embedding PHP Statements Within HTML Documents

• One way to use PHP is to embed PHP scripts within HTML tags in an HTML document. (prog1.php)

1. <html>2. <head> 3. <title>HTML With PHP Embedded</title> </head>4. <body> 5. <font size=5 color="blue">Welcome To My Page</font>6. <?php7. print "<br /> Using PHP gets easier as you keep practising it<br />";8. ?>9. </body></html>

(PHP code alone will run fine since system will construct an html output for browser automatically)

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Using Backslash (\) to Generate HTML Tags with print()

• Sometimes you want to output an HTML tag that also requires double quotation marks. – Use the backslash ("\") character to signal that the double

quotation marks themselves should beoutput:print "<font color=\"blue\">";

– The above statement would output: <font color="blue">

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Using Comments with PHP Scripts

• Comments enable you to include descriptive text along with the PHP script.– Comment lines are ignored when the script

runs; they do not slow down the run-time.– Comments have two common uses.

• Describe the overall script purpose.• Describe particularly tricky script lines.

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Using Comments with PHP Scripts

• 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 Comments (prog2.php)

1. <html> <head>2. <title> Generating HTML From PHP</title> </head>3. <body> <h1> Generating HTML From PHP</h1>4. <?php5. //6. // Example script to output HTML tags7. //8. print "Using PHP has <i>some advantages:</i>";9. print "<ul><li>Speed</li><li>Ease of Use </li><li>Functionality

</li></ul>"; //Output bullet list10. print "</body></html>";11. ?>

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Alternative Comment Syntax

• PHP allows a couple of additional ways to create comments.<?phpphpinfo(); # This is a built-in function?>

• Multiple line comments. <?php/*A script that gets information about thePHP version being used.*/phpinfo(); ?>

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Summary

• You 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

• 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 preceded by two forward slashes (//).

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Contents to be covered (Wk 1-8)• Variables, Operations and Expressions• Control statements

– if statements– for & while loops

• Arrays – 1-dimensional – 2-dimensional (tables)

• Functions• Form handling• File handling

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Resources

• www.w3schools.com/php/• www.php.net/manual/

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