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PHP 4 Vs PHP 5

2011-01-17T08:18:00.000-08:00

Object Model

The Object Model was present in PHP 4, but it was completely reworked in PHP
5. Here are some of the most important updates:

Passed by Reference

$pObject1 = new Object(); $pObject1->setName('Adam'); $pObject1->setAddress('http://www.talkphp.com/');
$pObject2 = new Object(); $pObject2->setName('Karl'); $pObject2->setAddress('http://www.talkphp.com/');

$pObject1 = new Object(); $pObject1->setName('Adam'); $pObject1->setAddress('http://www.talkphp.com/');
$pObject2 = clone $pObject1; $pObject2->setName('Karl');

Class Constants and Static Methods/Properties

Visibility
- Public - the most visible. Methods can be read by everyone and properties
  can be written or read by anyone.
- Protected - the members are visible only by the actual class they are
  a part of, as well as by subclasses and parent classes.
- Private - members are visible only to the actual class they are a part
  of.

Here is an example of how members are declared

<?php /** * Define ClassA */ class ClassA { public
$public = 'Public'; protected $protected = 'Protected'; private $private
= 'Private'; function printHello() { echo $this->public; echo $this->protected;
echo $this->private; } } $bor = new ClassA(); echo $bor->public; //
Will work echo $bor->protected; // Will give you a fatal error echo $bor->private;
// Will give you a fatal error $obj->printHello(); // Will display Public,
Protected and Private /** * Define ClassB */ class ClassB extends ClassA
{ // we can redeclare both the public and protected method, but we can't
redeclare the private one protected $protected = 'Protected2'; function printHello()
{ echo $this->public; echo $this->protected; echo $this->private;
} } $obj2 = new MyClass2(); echo $obj2->public; // Will work echo $obj2->private;
// Is now undefined echo $obj2->protected; // Will display a fatal error
$obj2->printHello(); // Will show you Public, Protected2, Undefined ?>

Unified Constructors and Destructors

Abstract Classes

class Message{

abstract class Message{

Interfaces

an example of a simple class:

class cow { function moo() { echo "moo, moo, moo …"; } }

and now we implement the interface in the class:

class cow implements animal{ function moo() { echo "moo, moo, moo …";
} function breath() { echo "cow is breathing …";} function eat() { echo "cow
is easting …";} }

Magic Methods

Finality

The __autoload function

function __autoload($class_name) { require_once "./includes/classes/$class_name.inc.php";
}

Introduction of Standard PHP Library (SPL)

PHP

XML

Miscellaneous Features and Updates

Here are the rest of the features, which do not fall into the previous categories.
- Type Hinting
- Exceptions
- E_STRICT Error Level
- New Extensions
  - SimpleXML - for an easier processing of XML data
  - DOM and XSL - their goal is to act in the place of DOMXML in PHP
    4. With them, XML usage is much easier.
  - PDO - a very good OO interface for interacting with databases
  - Hash - you now have access to a lot of hash functions beside the
    most popular ones - md 5 and sha1
- New Functions
  - array_combine() - it will create one array, using another two arrays
    - one for the keys and one for their values
  - array_walk_recursive() - a user function is applied recursively to
    all of the array members
  - ibase_db_info() - it will request the statistics for a database
  - ibase_name_result() - it will assign a name to a set of results
  - ibase_service_attach() - this function will connect you to the service
    manager
  - ibase_affected_rows() - it will return the number of rows affected
    by the previous query
  - iconv_strlen() - it will return the character count of a string
  - iconv_substr() - it will cut a part of a string
  - iconv_mime_decode_headers() - this function will decode several MIME
    headers at the same time
  - stream_copy_to_stream() - it will copy the data from one stream to
    another stream
  - stream_socket_get_name() - it will find the names of the local and
    remote sockets
  - stream_socket_sendto() - it will send a message to a socket, no matter
    if this socket is connected or not
  - date_sunset() - it will give you the time of the sunset for a given
    day and location
  - idate() - it will format the local time and date as an integer
  - date_sunrise() - it will give you the time of the sunrise for a given
    day and location
  - str_split() - it will convert a string to an array
  - strpbrk() - it will search the string for any set of characters specified

Compatibility Issues
- array_merge() will now give you warnings if any of the parameters are
  not arrays. In PHP4, you could get away with merging non-arrays with arrays
  (and the items would just be added if they were say, a string). Of course
  it was bad practice to do this to begin with, but it can cause headaches
  if you don't know about it.
- As discussed above, objects are now passed by references. If you want
  to copy an object, make sure to use the clone keyword.
- get_*() now returns names as they were defined. If a class was called
  MyTestClass, then get_class() would return that -- case sensitive! In PHP4,
  they were always returned in lowercase.
- An object with no properties is no longer considered "empty".
- In some cases classes must be declared before use. It only happens if
  some of the new features of PHP 5 (such as interfaces) are used.

PHP Programmer - Amit Shah

2008-02-11T00:34:00.001-08:00

Amit Shah provides you some information which will help to improve your knowledge.

By Amit Shah - PHP Programmer

PHP, PHP + MySQL, java script, AJAX, Programming, Web Development and services by - Amit Shah(C.E), Programming in cheap cost, Reliable services in PHP by Amit Shah, low cost for web development in PHP by Amit Shah, PHP Programmer.

What is PHP?

PHP stands for PHP: Hypertext Preprocessor

PHP is a server-side scripting language, like ASP

PHP scripts are executed on the server

PHP supports many databases (MySQL, Informix, Oracle, Sybase, Solid, PostgreSQL, Generic ODBC, etc.)

PHP is an open source software

PHP is free to download and use

What is a PHP File?

PHP files can contain text, HTML tags and scripts

PHP files are returned to the browser as plain HTML

PHP files have a file extension of ".php", ".php3", or ".phtml"

What is MySQL?

MySQL is a database server

MySQL is ideal for both small and large applications

MySQL supports standard SQL

MySQL compiles on a number of platforms

MySQL is free to download and use

PHP + MySQL

PHP combined with MySQL are cross-platform (you can develop in Windows and serve on a Unix platform)

Why PHP?

PHP runs on different platforms (Windows, Linux, Unix, etc.)

PHP is compatible with almost all servers used today (Apache, IIS, etc.)

PHP is FREE to download from the official PHP resource: www.php.net

PHP is easy to learn and runs efficiently on the server side

Variables in PHP

Variables are used for storing a values, like text strings, numbers or arrays.

When a variable is declared, it can be used over and over again in your scrilit.

All variables in PHP start with a $ sign symbol.

The correct way of declaring a variable in PHP:

PHP is a Loosely Typed Language

In PHP, a variable does not need to be declared before adding a value to it.

In the example above, you see that you do not have to tell PHP which data type the variable is.

PHP automatically converts the variable to the correct data type, depending on its value.

In a strongly typed programming language, you have to declare (define) the type and name of the variable before using it.

In PHP, the variable is declared automatically when you use it.

Naming Rules for Variables

A variable name must start with a letter or an underscore "_"

A variable name can only contain alpha-numeric characters and underscores (a-z, A-Z, 0-9, and _ )

A variable name should not contain spaces. If a variable name is more than one word, it should be separated with an underscore ($my_string), or with capitalization ($myString)

String Variables in PHP

String variables are used for values that contains characters.

In this chapter we are going to look at the most common functions and operators used to manipulate strings in PHP.

After we create a string we can manipulate it. A string can be used directly in a function or it can be stored in a variable.

Below, the PHP script assigns the text "Hello World" to a string variable called $txt:

The Concatenation Operator

There is only one string operator in PHP.

The concatenation operator (.) is used to put two string values together.

To concatenate two string variables together, use the concatenation operator:

Conditional Statements

Very often when you write code, you want to perform different actions for different decisions.

You can use conditional statements in your code to do this.

In PHP we have the following conditional statements:

if statement - use this statement to execute some code only if a specified condition is true

if...else statement - use this statement to execute some code if a condition is true and another code if the condition is false

if...elseif....else statement - use this statement to select one of several blocks of code to be executed

switch statement - use this statement to select one of many blocks of code to be executed

What is an Array?

You have already learnt that a variable is a storage area holding numbers and text. The problem is, a variable will hold only one value.

An array is a special variable, which can hold more than one value, at a time.

If you have a list of items (a list of car names, for example), storing the cars in single variables could look like this:

An array can hold all your variable values under a single name. And you can access the values by referring to the array name.

Each element in the array has its own index so that it can be easily accessed.

In PHP, there are three kind of arrays:

Numeric array - An array with a numeric index

Associative array - An array where each ID key is associated with a value

Multidimensional array - An array containing one or more arrays

Numeric Arrays

A numeric array stores each array element with a numeric index.

There are two methods to create a numeric array.

1. In the following example the index are automatically assigned (the index starts at 0):

Associative Arrays

An associative array, each ID key is associated with a value.

When storing data about specific named values, a numerical array is not always the best way to do it.

With associative arrays we can use the values as keys and assign values to them.

Multidimensional Arrays

In a multidimensional array, each element in the main array can also be an array. And each element in the sub-array can be an array, and so on.

PHP Loops

Often when you write code, you want the same block of code to run over and over again in a row. Instead of adding several almost equal lines in a script we can use loops to perform a task like this.

In PHP, we have the following looping statements:

while - loops through a block of code while a specified condition is true

do...while - loops through a block of code once, and then repeats the loop as long as a specified 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

PHP Functions

In this chapter we will show you how to create your own functions.

To keep the browser from executing a script when the page loads, you can put your script into a function.

A function will be executed by a call to the function.

You may call a function from anywhere within a page.

PHP Functions - Adding parameters

To add more functionality to a function, we can add parameters. A parameter is just like a variable.

Parameters are specified after the function name, inside the parentheses.