php app development 1

Web Scripting using PHP Server side scripting

So what is a Server Side Scripting Language? • Programming language code embedded into a web page PERL PHP PYTHON ASP

Different ways of scripting the Web • Programming language code embedded into a web page No scripting (plain markup) Client Side scripting Ser ver Side scripting Combination of the above (AJAX)

No Scripting example - how it works... User on a machine somewhere Ser ver machine

User types in a URL for a page with no programming code inside

User types in a URL for a page with no programming code inside Uniform Resource Locator

Request is sent to ser ver using HTTP

Request is sent to ser ver using HTTP Hypertext Transfer Protocol

Ser ver soft ware ﬁnds the page

Browser renders / displays the page

User types in a URL for a page with PHP code inside

Server side scripting languages • Executes in the ser ver • Before the page is sent from server to browser • Ser ver side code is not visible in the client • Ser ver side code can access resources on the server side

Browser Web ser ver Database ser ver

Web ser ver executes code Queries database ser ver

So why PHP? PERL PHP PYTHON ASP

PHP usage ... • Source: PHP programming 2nd Ed.

PHP compared to others ... • Source: www.securityspace.com

Books - core syntax Programming PHP, Second Edition PHP in a Nutshell By Kevin Tatroe, Rasmus Lerdorf, By Paul Hudson Peter MacIntyre First Edition October 2005 Second Edition April 2006 ** Recommended

Books - learning / tutorial based Learning PHP 5 Learning PHP and MySQL By David Sklar By Michele Davis, Jon Phillips First Edition June 2004 First Edition June 2006

Other texts.. • There are other publishers / texts (trade books) • Look for books that cover PHP 5 • Open source, server side languages can rapidly develop • Features added or deprecated rapidly

PHP development PHP 5 PHP 4 PHP 3 PHP 1 • 5 versions in 10 years

Language basics • Embedding PHP in Web pages • Whitespace and Line breaks • Statements and semicolons • Comments • Literals / names • Identiﬁers • Keywords • Data types

Language basics • Embedding PHP in Web pages • Whitespace and Line breaks • Statements and semicolons • Comments • Literals / names • Identiﬁers • Keywords • Data types Much of this material is explained in PHP programming 2nd Ed. Chap 1 & 2

Embedding PHP in web pages Use <?php and ?> to <?php surround the php code statement; statement; statement ?>

Embedding PHP in web pages <?php statement;statement; statement; statement; statement;statement; ?> In general whitespace doesn’t matter Use indenting and separate lines to create readable code

The legendary Hello World program <!DOCTYPE HTML PUBLIC "-//W3C/DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <title>This is the first PHP program</title> </head> <body> <?php print "Hello World!"; ?> </body> </html>

The legendary Hello World program <!DOCTYPE HTML PUBLIC "-//W3C/DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <title>This is the first PHP program</title> </head> <body> print sends a sequence of <?php print "Hello World!"; characters to the output ?> The sequence here is </body> indicated by start and </html> end quotes

PHP can be put ‘ nywhere’.. a All the php blocks are processed <html> <?php ... ?> before the page is sent <head> <?php ... ?> <title>... <?php ... ?> ...</title> </head> <body> <?php ... ?> </body> </html>

PHP can be put ‘ nywhere’.. but works in sequence a <html> <?php ... ?> Starting at the top <head> <?php ... ?> <title>... <?php ... ?> ...</title> </head> <body> <?php ... ?> Working down to the bottom </body> </html>

Statements and semicolons Use ; to separate <?php statements statement; statement; statement; ?>

All of these would work the same way... <?php statement; statement;statement ?> <?php statement; statement;statement; ?> <?php statement; statement; This is the best way of statement; laying the code out ?>

Comments Many different ways to add comments Comment Source Action // C++ Comments to EOL # Unix shell scripting Comments to EOL /* and */ C Comments out a block

Comments <?php php statement; // A comment here php statement; # Another comment here /* A series of lines with comments ignored by the PHP processor */ php statement; ?>

Comments <?php php statement; // A comment here php statement; # Another comment here /* A series of lines with comments ignored by the PHP processor */ php statement; ?> Everything in red is ignored by the PHP interpreter

Language basics • Embedding PHP in Web pages ✔ • Whitespace and Line breaks ✔ • Statements and semicolons ✔ • Comments ✔ • Literals / names • Identiﬁers • Keywords • Data types

Literals A data value that appears directly in the program 2001 An integer 0xFE Hexadecimal number 1.4142 Float “Hello World” String ‘Hi’ String true Bool null built in ‘no value’ symbol

Identiﬁers Identiﬁers (or names) in PHP must - Begin with an ASCII letter (uppercase or lowercase) or begin with the underscore character _ or any character bet ween ASCII 0x7F to 0xFF followed by any of these characters and the digits 0-9

Variables Variables in PHP are identiﬁers preﬁxed by $ $bill $value_count $anothervalue3 Valid $THIS_IS_NOT_A_GOOD_IDEA $_underscore $not valid Invalid $[ $3wa

Case sensitivity - names we deﬁne are case sensitive $value Three different names $VALUE $vaLUE

Variables We use variables for items of data that will change as the program runs Choose a sensible name and have as many as you like $total_income $bill $salary $month $total $percentage_increase

Variables When we declare a variable, a space is reserved and labelled for that item (in memory) $bill $bill

Variables To give it a value, use the equals sign $bill $bill

Variables To give it a value, use the equals sign $bill = 42 $bill

Variables To give it a value, use the equals sign $bill = 42 42 $bill

Variables To give it a value, use the equals sign $bill = 57.98 $bill

Variables To give it a value, use the equals sign $bill = 57.98 57.98 $bill

Variables To give it a value, use the equals sign $bill = “No payment” $bill

Variables To give it a value, use the equals sign $bill = “No payment” “No payment” $bill

Variables If a value is changed, the old value is over written $bill $bill

Variables If a value is changed, the old value is over written $bill = 42; $bill

Variables If a value is changed, the old value is over written $bill = 42; 42 $bill

Variables If a value is changed, the old value is over written $bill = 42; 42 $bill = 58; $bill

Variables If a value is changed, the old value is over written $bill = 42; 58 $bill = 58; $bill

Variables Sometimes we use the old value to recalculate the new value $bill $bill

Variables Sometimes we use the old value to recalculate the new value $bill = 42; $bill

Variables Sometimes we use the old value to recalculate the new value $bill = 42; 42 $bill

Variables Sometimes we use the old value to recalculate the new value $bill = 42; 42 $bill = $bill*2 ; $bill

Variables Sometimes we use the old value to recalculate the new value $bill = 42; 84 $bill = $bill*2 ; $bill

Variables Some languages are very strict about what kinds of data are stored in variables - PHP doesn’t care $bill=42; Stores an integer $bill=42; $bill=”Now its a string”; print $bull;

Variables Some languages are very strict about what kinds of data are stored in variables - PHP doesn’t care $bill=42; Stores an integer $bill=42; Over writes with a string $bill=”Now its a string”; print $bull;

Variables Some languages are very strict about what kinds of data are stored in variables - PHP doesn’t care $bill=42; Stores an integer $bill=42; Over writes with a string $bill=”Now its a string”; Whoops - made a mistake print $bull; but it still works

Keywords _CLASS_ _ Declare extends print( ) _ _FILE_ _ Default ﬁnal private Reserved by _ _FUNCTION_ _ die( ) for protected the language _ _LINE_ _ Do foreach public for core _ _METHOD_ _ echo( ) function require( ) Else global functionality Abstract And elseif if require_once( ) array( ) empty( ) implements return( ) As enddeclare include( ) static Break endfor include_once( ) switch Also - can’t Case catch endforeach interface tHRow endif isset( ) use a built in cfunction endswitch list( ) TRy unset( ) function Class endwhile new use clone name as a Const eval( ) old_function var exception Or variable Continue exit( ) php_user_ﬁlter while xor

Data types PHP provides 8 types scalar (single-value) compound integers arrays ﬂoating-point objects string booleans Two are special - resource and NULL

Integers Whole numbers - range depends on the C compiler that PHP was made in (compiled in) Typically +2,147,483,647 to -2,147,483,647 Octal 0755 Hexadecimal 0xFF Larger integers get converted to ﬂoats automatically

Floating-Point Numbers Real numbers - again range is implementation speciﬁc Typically 1.7E-308 to 1.7E+308 with 15 digits of accuracy Examples 3.14, 0.017, -7.1, 0.314E1, 17.0E-3

Strings Delimited by either single or double quotes ‘here is a string’ “here is another string”

Strings - single quotes You can use single quotes to enclose double quotes $outputstring=‘He then said “Goodbye” and left’; Useful for easily printing HTML attributes $outputstring=‘<a href=”http:/www.bbc.co.uk”>BBC</a>’;

Strings - double quotes You can use double quotes to enclose single quotes $outputstring=”He then said ‘Goodbye’ and left”;

Operators Standard arithmetic operators: +, -, *, /, % .. Concatenation operator: . $outputstring=”He then said “.$quote; Any non-string value is converted to a string before the concatenation.

Operators $aBool=true; $anInt=156; $aFloat=12.56; $anotherFloat=12.2E6; $massiveFloat=12.2E-78; print "The bool printed looks like this: ".$aBool." "; print "The int printed looks like this: ".$anInt." "; print "The (smaller) float printed looks like this: ".$aFloat." "; print "The larger float printed looks like this: ".$anotherFloat." "; print "The even larger float printed looks like this: ".$massiveFloat." ";

php app development 1

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