PHP - PHP5

							          PHP5

      By Amit R. Kurmi
           Roll No 3429
Seminar guide : H.A.HINGOLIWALA
Internal Examiner : M.V.GAIKWAD
     1. History of PHP and Introduction
                   to PHP5
   PHP is a computer scripting language originally designed for producing dynamic
    web pages.
    The name PHP is a recursive acronym for PHP: Hypertext Preprocessor.
   The main implementation is produced by The PHP Group and released under the
    PHP License.
   It is considered to be free software by the Free Software Foundation.
    PHP 5 included new features such as:
   Improved support for object-oriented programming
   The PHP Data Objects extension, which defines a lightweight and consistent
    interface for accessing databases
   Performance enhancements
   Better support for MySQL and MSSQL
   Embedded support for SQLite
   Integrated SOAP support
   Data iterators
   Error handling via exceptions
                             2.Usage
   PHP is a widely-used general-purpose scripting
    language that is especially suited for Web
    development and can be embedded into HTML.
   It can also be used for command-line scripting and
    client-side GUI applications.
   2.1 Server-side scripting
          Originally designed to create dynamic web pages, PHP5's
           principal focus is server-side scripting.
          PHP5 model can be compared to other server-side scripting
           languages such as Microsoft's ASP.NET system, Sun
           Microsystems' JavaServer Pages, and mod perl as they all provide
           dynamic content to the client from a web server.
          As of April 2007, over 20 million Internet domains were hosted on
           servers with PHP installed.
   2.2 Command-line scripting
        PHP5 also provides a command line interface SAPI
        for developing shell and desktop applications,
        daemons, log parsing .
   2.3 Client-side GUI applications
        PHP5 provides bindings to GUI libraries such as
        GTK+(with PHP-GTK), Qt with PHP-Qt and text mode
        libraries like ncurses in order to facilitate development
        of a broader range of cross-platform GUI applications.
                      3. Syntax
  The usual Hello World code example for PHP5 is:
<?php
echo "Hello World!\n";
?>
 PHP only parses code within its delimiters.

 Delimiters supported by php5 are,

 <?php and ?> (open and close delimiters )

   <script language="php"> </script> (style delimiters )
   (<? or <?= and ?>)        (Short tags )
   (<% or <%= and %>)       (ASP style tags )
   3.1 Data types
   There are eight data types in PHP:
   Integer
   Double
   Boolean
   String
   Object
   Array
   Null
   Resource
3.2 Functions
   PHP has hundreds of base functions and several thousand from extensions.
   User-defined functions can be created at any time and without being prototyped.
   Example:
<?php
    function hello() //defining function
          { echo "Hello World!\n";
          }
    hello(); // Calling function hello
?>
3.3 Objects
   In previous versions of PHP, objects were handled like primitive types. The
    drawback of this method was that the whole object was copied when a variable was
    assigned or passed as a parameter to a method.
   In php5, objects are referenced by handle, and not by value.
                         4. Resources
   4.1 Libraries
    PHP includes a large number of free and open source libraries
    with the core build.
   4.2 Extensions
       PHP allows developers to write extensions in C to add functionality to
        the PHP language.
       These can then be compiled into PHP or loaded dynamically at
        runtime.
   4.3 Debuggers and profilers
       Debuggers and profilers allow developers to analyze running PHP code
        for potential and noted software bugs and bottlenecks.
        Examples of such software for PHP include APD and Xdebug.
    4.4 Templating engines
    Templating engines provide macros that allow PHP
    applications to uniformly identify common variables.
    One popular templating engine is Smarty.
   4.5 PEAR
   The PHP Extension and Application Repository
    (PEAR) project aims to provide reusable libraries and
    components for PHP development.
    PEAR projects are usually written in PHP code using
    the Object-oriented programming paradigm.
            5 . PHP 5 OO Language
  5.1 Declaring A Class
class MyClass {
        ... // List of methods
        ...
        ... // List of properties
        ...
        }
 5.2 THE new KEYWORD AND CONSTRUCTORS
       Instances of classes are created using the new keyword.
       Duringng the new call , a new object is allocated with its own copies of
        the properties defined in the class you requested, and then the
        constructor of the object is called .
 5.3 DESTRUCTORS
 They are called when the object is being destroyed

 There are two situations where your destructor
  might be called: during your script’s execution
  when all references to an object are destroyed, or
  when the end of the script is reached .
 5.4 CLASS CONSTANTS

 You can now define constants inside classes.

 Class constants are always case-sensitive.
   5.6 CLONING OBJECTS
   Used to create a copy of the object.
   This builtin operator automatically creates a new instance of the object
    with its own copy of the properties.
   5.7 parent:: AND self::
   PHP supports two reserved class names
   self:: refers to the current class and it is usually used to access
    static members, methods, and constants.
    parent:: refers to the parent class and it is most often used when
    wanting to call the parent constructor or methods.
   5.8 INTERFACES
   PHP chose interfaces as an alternative to multiple inheritance.
   class A implements B, C, ... {
   ...
   }
   5.9 INHERITANCE OF INTERFACES
   Interfaces may inherit from other interfaces.
     interface I1 extends I2, I3, ... {
     ...
     }
    5.10 final METHODS-These methods can’t be overridden.
   5.11 final CLASSES- It disallows inheriting from this class.
   5.12 autoload()
   When writing object-oriented code, it is often customary to put each
    class in its own source file.
   The downside is that you often have to include tons and tons of source
    files, which can be a pain
   __autoload() solves this problem by not requiring you to include
    classes you are about to use.
6.How to Write a Web Application
           with PHP
   6.1 Introduction
   PHP makes web applications dynamic, enabling users
    to interact with the site.
   The web application collects information from the user
    by means of HTML forms and processes it.
   6.2 Embedding Into HTML
   PHP doesn’t have to be embedded in an HTML file you
    can create a PHP file that includes no HTML.
    PHP was developed primarily for web use, to be embedded
    in HTML files as a templating language.
   When PHP code is included in a file, the file is given the
    PHP extension usually .php, but a different extensions,
    such as .phtml or .php5 can be used.
        6.4 TECHNIQUES TO MAKE
              SCRIPTS “SAFE”
   There is only one solution to keeping your scripts
    running safe: Do not trust users.
       6.4.1 Input Validation
       The term simply means that you need to check all input
        that comes from the user, whether the data comes from
        cookies, GET, or POST data.
       First, turn off register_globals in php.ini and set the
        error_level to the highest possible value (E_ALL |
        E_STRICT).
       The register_globals setting stops the registration of request
        data (Cookie, Session, GET, and POST variables) as
        globalvariables in your script; the high error_level setting
        will enable notices for uninitialized variables.
   6.4.2 HMAC Verification
   If you need to prevent bad guys from tampering
    with variables passed in the URL, use HMAC
    (Keyed-Hashing for Message Authentication).
   The HMAC method is proven to be stronger
    cryptographically .
   The HMAC algorithm uses a secret key in a two-
    step hashing of plain text .
   6.5 COOKIES
   One simple way to maintain data between the different
    pages in a web application is with cookies.
   Cookies are sent by PHP through the web server with the
    setcookie() function and are stored in the browser.
   6.6 SESSIONS
   A PHP session allows an application to store information
    for the current “session”.
   PHP creates a session ID that is an MD5 hash of the remote
    IP address, the current time, and some extra randomness
    represented in a hexadecimal string. This session ID can be
    passed in a cookie or added to all URLs to navigate your
    application.
           6.7 ARCHITECTURE

   6.7.1 One Script Serves All
   One script serves all stands for the idea that one script,
    usually index.php, handles all the requests for all different
    pages.
   6.7.2 One Script per Function
   Each function is stored in a different script and accessed
    through its URL
   6.7.3 Separating Logic from Layout
   You always need to strive to separate your logic from the
    layout of your pages. There are a few ways to do this—for
    example, with a templating engine or you can also use
    your own templating method .
            7.Future development

   Namespace support will be added.
   Native Unicode support will be added.
   The magic_quotes option will be removed.
   The HTTP_*_VARS global variables will be
    removed.
   The register_globals option will be removed.
   The safe_mode option will be removed.
   Late static binding will be added.