Basics PHP

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Basics PHP

  1. 1. PHP Basics Presented By Sajeer.K.P
  2. 2. Server-Side Scripting  What is a script?  Collection of program or sequence of instructions  Processed/interpreted by another program  Rather than by a processor  Client-side  Server-side  In server-side scripting, PHP ASP.net - Processed by the server Like: Apache, ColdFusion, ISAPI and Microsoft's IIS on Windows.  Client-side scripting such as JavaScript runs on the web browser.  Important fot dynamic HTML
  3. 3. Introduction to PHP PHP stands for: Hypertext PreProcessor Developed by Rasmus Lerdorf in 1994(Personal Home Page) – Originally a set of Perl scripts known as the “Personal Home Page” tools • Source code released in 1995 • PHP 3 in 1997-98 by Andi Gutmans and Zeev Suraski • Latest version 5.5.1 • It is a powerful server-side scripting language for creating dynamic and interactive websites. • It is an open source software, which is widely used and free to download and use (php.net). • It is an efficient alternative to competitors such as Microsoft's ASP.
  4. 4. Introduction to PHP • PHP is perfectly suited for Web development and can be embedded directly into the HTML code. • The PHP syntax is very similar to JavaScript, Perl and C. • PHP is often used together with Apache (web server) on various operating systems. It also supports ISAPI and can be used with Microsoft's IIS on Windows. • PHP supports many databases (MySQL, Informix, Oracle, Sybase, Solid, PostgreSQL, Generic ODBC, etc.)
  5. 5. Introduction to PHP • What is a PHPFile? • PHP files have a file extension of .php, .phtml, .php4 .php3, .php5, .phps • PHP files can contain text, HTML tags and scripts • PHP files are returned to the browser as plain HTML 
  6. 6. Introduction to PHP What you need to develop PHPApplication: • Install Apache (or IIS) on your own server, install PHP, and MySQL • OR • Install Wampserver2 (a bundle of PHP, Apache, and MySql server) on your own server/machine
  7. 7. PHP Installation Downloads Free Download  PHP: http://www.php.net/downloads.php  MySQL Database: http://www.mysql.com/downloads/index.html  Apache Server: http://httpd.apache.org/download.cgi • How to install and configure apache • Here is a link to a good tutorial from PHP.net on how to install PHP5: http://www.php.net/manual/en/install.php
  8. 8. How PHP is Processed • When a PHP document is requested of a server, the server will send the document first to a PHP processor • Two modes of operation – Copy mode in which plain HTML is copied to the output – Interpret mode in which PHP code is interpreted and the output from that code sent to output – The client never sees PHP code, only the output produced by the code
  9. 9. Basic PHP Syntax • starts with <?php and ends with ?> <?php ……………. ?> – Other options are: 1. <? ……………… ?> or<?= ?>(shortened forms) 2. <script language=”php”> ... </script> • There are three basic statements to output text with PHP: echo, print, and printf. Example: echo 'This is a <b>test</b>!'; • Comments: – # – // – /* . . . * /
  10. 10. Basic PHP Syntax • PHP statements are terminated with semicolons ; • Curly braces, { } are used to create compound statements • PHP has typical scripting language characteristics – Dynamic typing, un-typed variables – Associative arrays – Pattern matching – Extensive libraries • Primitives, Operations, Expressions – Four scalar types: boolean, integer, double, string – Two compound types: array, object – Two special types: resource and NULL
  11. 11. Basic PHP Syntax Example 1 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>Simple PHP Example</title> <body> <?php echo "Hello Class of 2011. This is my first PHP Script"; echo "<br />"; print "<b><i>What have you learnt and how many friends have you made?</i></b>"; echo "<br /><a href='PHP I-BSIC.ppt'>PHP BASIC</a>"; ?> </body> </html>
  12. 12. PHP Language Basics • Constants, Data Types and Variables • Constants define a string or numeric value • Constants do not begin with a dollar sign • Examples: • define(“COMPANY”, “Acme Enterprises”); • define(“YELLOW”, “#FFFF00”); • define(“YELLOW”, “#FFFF00”); • define(“PI”, 3.14); • define(“NL”, “<br>n”); Using a constant
  13. 13. PHP Language Basics • Constants, Data Types and Variables Data types • Integers, doubles and strings – isValid = true; // Boolean – 25 // Integer – 3.14 // Double – ‘Four’ // String – “Total value” // Another string
  14. 14. PHP Language Basics • Constants, Data Types and Variables Data types • Strings and type conversion – $street = 123; – $street = $street . “ Main Street”; – $city = ‘Naperville’; $state = ‘IL’; – $address = $street; – $address = $address . NL . “$city, $state”; – $number = $address + 1; // $number equals 124
  15. 15. PHP Language Basics • Constants, Data Types and Variables Data types • Arrays – Perl-like syntax » $arr = array("foo" => "bar", 12 => true); – same as » $arr[“foo”] = “bar”; » $arr[12] = true;
  16. 16. PHP Language Basics • Constants, Data Types and Variables • Arrays (cont.) – <?php $arr = array("somearray" => array(6 => 5, 13 => 9, "a" => 42)); echo $arr["somearray"][6]; // 5 echo $arr["somearray"][13]; // 9 echo $arr["somearray"]["a"]; // 42 ?>
  17. 17. PHP Language Basics • Constants, Data Types and Variables Operators – Contains all of the operators like in C and Perl (even the ternary) Statements – if, if/elseif – Switch/case – for, while, and do/while loops – Include and require statements for code reuse
  18. 18. PHP Variables • Variables are used for storing values, such as numbers, strings or function results, so that they can be used many times in a script. • All variables in PHP start with a $ sign symbol. • Variables are assigned using the assignment operator "=" • Variable names are case sensitive in PHP: $name is not the same as $NAME or $Name. • Variable naming rules similar to variable naming rules in other programming languages • In PHP a variable does not need to be declared before being set. PHP is a Loosely Typed Language.
  19. 19. Strings in PHP • a string is a sequence of letters, symbols, characters and arithmetic values or combination of all tied together in single or double quotes. • String literals are enclosed in single or double quotes • Example: <?php $sum = 20; echo 'the sum is: $sum'; echo "<br />"; echo "the sum is: $sum"; echo "<br />"; echo '<input type="text" name="first_name" id="first_name">'; ?> – Double quoted strings have escape sequences (such as /n or /r) interpreted and variables interpolated (substituted) – Single quoted strings have neither escape sequence interpretation nor variable interpolation – A literal $ sign in a double quoted string must be escaped with a backslash, – Double-quoted strings can cover multiple lines
  20. 20. Escaping quotes with in quotes Example 1: <?php $str = ""This is a PHP string examples quotes""; echo $str; ?> Example 2 <?php $str = 'It's a nice day today.'; echo $str; ?>
  21. 21. The Concatenation Operator • The concatenation operator (.)  is used to put two string values together. • Example: <?php $txt1="Hello Everyone,"; $txt2="1234 is Dan’s home address"; echo $txt1.$txt2; ?>
  22. 22. PHP Operators  Operators are used to operate on values.  List of PHP Operators:  Similar to Other programming language  Arithamatic  Assignment  Bitwise  Comparison  Incrementing/decrementing  Logical  Array
  23. 23. PHP Function  In php a function is a predefined set of commands that are carried out when the function is called.  The real power of PHP comes from its functions.  PHP has more than 700 built-in or predefine functions for you to use.  Complete php string reference  You can write your own functions
  24. 24. Using Built-in Functions • Useful PHPString Functions <?php echo strlen("Hello world!");//prints string length echo "<br />"; echo strpos("Hello world!","world"); //Prints //position of a word ?> </body> </html>
  25. 25. Basic PHP Syntax  Inserting external files:  PHP provides four functions that enable you to insert code from external files: include() or require() include_once() or require_once() functions. • E.g.  include("table2.php"); – Includedfiles start incopymode
  26. 26. Using Built-in Function  Examples: Inserting external files: PHP provides four functions that enable you to insert code from external files: include() or require() include_once() or require_once() functions. A sample include file called add.php <html> <body> <?php function add( $x, $y ) { return $x + $y; } ?> <h1>Welcome to my home page</h1> <p>Some text</p> </body> </html> Using the include function <?php include('add.php'); echo add(2, 2); ?>
  27. 27. Using Built-in Function  Inserting external files - continued:  The functions are identical in every way, except how they handle errors.  The include() and include_once() functions generates a warning (but the script will continue execution)  The require() and require_once() functions generates a fatal error (and the script execution will stop after the error).  These functions are used to create functions, headers, footers, or elements that can be reused on multiple pages.  This can save the developer a considerable amount of time for updating/editing.
  28. 28. Defining and Referencing a Function Syntax function functionname () { your code } Example: <html> <body> <?php Function Name() { echo "Ben John"; } Name(); ?> </body> </html>
  29. 29. Conditional Statements 1. The If...Else Statement Syntax if (co nditio n) co de to be e xe cute d if co nditio n is true ; else co de to be e xe cute d if co nditio n is false ; <?php $d=date("D"); if ($d=="Fri") echo "Have a nice weekend!"; else echo "Have a nice day!"; ?> If more than one line should be executed if a condition is true/false, the lines should be enclosed within curly braces:
  30. 30. Conditional Statements 2. The ElseIf Statement • If you want to execute some code if one of several conditions is true use the elseif statement Syntax if (co nditio n) co de to be e xe cute d if co nditio n is true ; elseif (co nditio n) co de to be e xe cute d if co nditio n is true ; else co de to be e xe cute d if co nditio n is false ;
  31. 31. PHP Switch Statement • If you want to select one of many blocks of code to be executed, use the Switch statement. • The switch statement is used to avoid long blocks of if..elseif..else code. Syntax switch (e xpre ssio n) { case labe l1 : co de to be e xe cute d if e xpre ssio n = labe l1 ; break; case labe l2: co de to be e xe cute d if e xpre ssio n = labe l2; break; default: co de to be e xe cute d if e xpre ssio n is diffe re nt fro m bo th labe l1 and labe l2; }
  32. 32. PHP Looping • Looping statements in PHP are used to execute the same block of code a specified number of times. • In PHP we have the following looping statements: – while - loops through a block of code if and as long as a specified condition is true – do...while - loops through a block of code once, and then repeats the loop as long as a special condition is true – for- loops through a block of code a specified number of times – foreach - loops through a block of code for each element in an array
  33. 33. PHP Arrays  An array can store one or more values in a single variable name.  There are three different kind of arrays:  Numeric array - An array with a numeric ID key  Associative array - An array where each ID key is associated with a value  Multidimensional array - An array containing one or more arrays
  34. 34. Tricks and Tips • Coding Prototype your web pages first • Separate the design of the site from the coding Turn repetitive code into functions • Makes for more maintainable and reusable code Turn grunt code into functions • Database access, configuration file access
  35. 35. Tricks and Tips • Debugging Feature: PHP is not a strongly typed language • Variables can be created anywhere in your code Undocumented Feature: PHP is not a strongly typed language • Typos in variable names will cause stuff to happen
  36. 36. Tricks and Tips • Debugging Use scripts to dump form and session variables • Write scripts to dump data to discover bad or missing data
  37. 37. Tricks and Tips • Development Tools Color coding editors • vim, Emacs, Visual SlickEdit IDEs • Windows – Macromedia Dreamweaver – Allaire Homesite – Zend’s PHPEdit – netbeans • Linux – ???
  38. 38. PHP and the Web  www.intellibitz.com Is typed in firefox  Firefox sends a message over the internet to the computer named www.intellibitz.com  Apache, a program running on www.intellibitz.com, gets the message and asks the PHP interpreter, another program running on the www.intellibitz.com computer, “what does /index.php look like?”
  39. 39. PHP and the Web  The PHP interpreter reads the file /var/www/index.php from disk drive  The PHP interpreter runs the commands in index.php, possibly exchanging data with a database program such as MySQL  The PHP interpreter takes the index.php program output and sends it back to Apache as answer
  40. 40. PHP and the Web  Apache sends the page contents it got from the PHP interpreter back to your computer over the Internet in response to Firefox  Firefox displays the page on the screen, following the instructions of the HTML tags in the page
  41. 41. Security •About 30% of all vulnerabilities listed on the National Vulnerability Database are linked to PHP. •These vulnerabilities are caused mostly by not following best practice programming rules; technical security flaws of the language itself or of its core libraries are not frequent •programmers make mistakes, some languages include taint checking to automatically detect the lack of input validation which induces many issues. •There are advanced protection patches such as Suhosin and Hardening- Patch, especially designed for web hosting environments.
  42. 42. Questions? – Any Questions • www.php.net – Community • www.phpbuilder.com: articles on PHP, discussion forums – Newsgroups • comp.lang.php

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