An Introduction to PHP

The University of Tennessee at Chattanooga

C. Daniel Chase

“An introduction to basic PHP use with a focus on the power of dynamic pages in comparison to static HTML, including a short history of PHP, statement syntax, basic program logic statements and data types, simple PHP pages and HTML forms.”

Overview

● Short History● Sample PHP Code & Output● Documentation Resources● Web Applications● Language Basics● Functions● Arrays● A Real World Application

The History of PHP

● Created by Rasmus Lerdorf● June 1995 –

Personal Home Page Tools (PHP Tools) version 1.0 released– CGI-based– Original intent was Not to create a scripting language

● April 1996 -PHP version 2 (PHP/FI) released– Now called a 'scripting language'

The History of PHP

● Zeev Suraski & Andi Gutmans volunteer to the underlying parsing engine

● June 1998 - PHP Version 3.0 released– In use on over 70,000 web sites

● May 2000 - PHP Version 4.0 released– Zend Engine introduced

● July 2004 – PHP Version 5.0 released

PHP Popularity

● August 2004– 16,946,328 Domains– 1,348,793 IP Addresses

A Sample Program

● The traditional... “Hello World”● The Source

Things to notice

● File type: .php● Normal HTML tags● <?php ... ?> Tag surround PHP sections● PHP lines end with semicolon ; usually...● Your first PHP command: echo● Comment lines

– shell style #– c++ style //– c style /* ... */

● White space● Case sensitivity: Variables Only

Resources

● Main site - PHP.net● Commercial Support - Zend.com● Smarty Template Engine – Smarty.php.net● Documentation

– All versions - php.net/docs.php– Web-based– Download

● HTML● Windows CHM

Data Types

● Integers– decimal default– octal: leading 0 and only 0-7– hex: 0x prefix and 0-F– is_int()

● Floating-Point Numbers– normal: 3.14– scientific notation: 0.314E1– is_float() or is_real()

Data Types...

● Strings– single quote delimiter – no expansion– double quote delimiter – variables expanded– escape sequences with \– is_string()

● Booleans– true– false– is_bool()

Data Types...

● Arrays– $person[0] = “Edison”;$person[1] = “Wankel”;

– $creator['Light bulb'] = “Edison”;$creator['Rotary Engine'] = “Wankel”;

– $person = array('Edison', 'Wankel');$creator = array('Light bulb' => 'Edison', 'Rotary Engine' => 'Wankel');

– Looping:foreach ($person as $name) { echo “Hello, $name\n”;}foreach (creator as $invention => $inventor) { echo “$inventor created the $invention\n”;}

Other Data Types

● Objects● Resources● null

Variables

● Names– Begin with $– Case Sensitive– First character must be Alpha, underscore (_) or ASCII

0x7f to 0xff– Other characters add digits also

● Variable Variables– Name of variable stored in aother variable– $foo = 'bar';$$foo = 'baz';

● Variable References– $black =& $white;

Scope

● Local – declared Inside a function● global – declared Outside a function● static – retains value between calls● Function parameters● Sample Variables

Operators

● Addition (+)● Subtraction (-)● Multiplication (*)● Division (/)● Modulus (%)● Negation (-)● String concatenation (.)● Pre- & Post-increment (++)● Pre & Post-decrement (--)

● Equality (==)● Identical (===)● Inequality (!= or <>)● Not identical (!==)● Greater than (>)● Less that (<)● Greater than or equal (>=)● Less than or equal (<=)● Logical AND (&&, and)● Logical OR (||, or)● Logical XOR (xor)● Logical negation (!)

Assignment

● Assignment (=)● Plus-equals (+=)● Minus-equals (-=)● Divide-equals (/=)● Multiply-equals (*=)● Modulus-equals (%=)

Miscellaneous Operators

● Error suppression (@)● Execution (` ... `)● Conditional or Ternary operator (?:)

Flow Control - if

● if ($good) { print ('Dandy!); $real_good = true;} elseif ($error) print ('Oh, No!');else print (“I'm ambivalent...”);

● if ($user_validated) : print ('Welcome!); $greeted = 1;else : print (“Access Forbidden!”); exit;endif;

Flow Control - switch

● switch ($name) { case 'test1': // do something break; case 'test2': // do something else break; case 'test3': // do something different break;}

● Or use : and endswitch instead of block

Flow Control - while

● $total = 0;$i = 1;while ($i < 10) { $total += $i;}

● while ($i < 10) : $total += $i;endwhile;

● break [levels]● continue [levels]● do ... while

Flow Control - for

● for ($counter = 0; $counter < 10; $counter++) echo “Counter is $counter”;

● endfor● break● continue● foreach ($array as $current) { echo $current;}

● foreach ($array as $key => $value) {echo “Value or $key is $value”;}

● exit and return

Including Code

● include header.php● require footer.php● URL's:include 'http://some.other.host/header.php'

Web Applications

● Retrieving Form data: $_REQUEST['field name']● Retrieving Server info: $_SERVER['field name']● Sending headers: header('location: http://localhost/')

● Cookies: setcookie(name [, value[, expire [, path [, domain [, secure]]]]]]);

● Retrieve Cookies: $_COOKIE['cookie name']