PHP working with Files and Directory

Below are some of the important methods used when working or manipulating the files or folders

parse_ini_file($filename)
parse_ini_file() loads in the ini file specified in filename, and returns the settings in it in an associative array.
Example
// Parse without sections
$ini_array = parse_ini_file("sample.ini");
print_r($ini_array);

// Parse with sections
$ini_array = parse_ini_file("sample.ini", true);
print_r($ini_array);
O/P
Array
(
[one] => 1
[five] => 5
[animal] => Dodo bird
[path] => /usr/local/bin
[URL] => http://www.example.com/~username
[phpversion] => Array
(
[0] => 5.0
[1] => 5.1
[2] => 5.2
[3] => 5.3
)

)
Array
(
[first_section] => Array
(
[one] => 1
[five] => 5
[animal] => Dodo bird
)

[second_section] => Array
(
[path] => /usr/local/bin
[URL] => http://www.example.com/~username
)
)

basename($path)
Given a string containing a path to a file, this function will return the base name of the file.
Example
$path = "/home/httpd/html/index.php";
$file = basename($path); // $file is set to "index.php"

dirname($path)
Given a string containing a path to a file, this function will return the name of the directory.
example
$path = "/etc/passwd";
$file = dirname($path); // $file is set to "/etc"

pathinfo($_SERVER['PHP_SELF'])
pathinfo() returns an associative array containing information about path.
Example
$path_parts = pathinfo('/www/htdocs/inc/lib.inc.php');

echo $path_parts['dirname'], "\n"; //www/htdocs/inc
echo $path_parts['basename'], "\n"; //lib.inc.php
echo $path_parts['extension'], "\n"; //php
echo $path_parts['filename'], "\n"; // lib.inc

realpath($path)
realpath() expands all symbolic links and resolves references to '/./', '/../' and extra '/' characters in the input path and return the canonicalized absolute pathname
Example
echo realpath('/windows/system32'); //C:\WINDOWS\System32

getcwd()
Gets the current working directory.

file_exists
hecks whether a file or directory exists

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PHP Magic Methods

These are the following magic methods available

__construct, __destruct, __call, __callStatic, __get, __set, __isset, __unset, __sleep, __wakeup, __toString, __invoke, __set_state and __clone are magical in PHP classes.

PHP reserves all function names starting with __ as magical.

__sleep
serialize() checks if your class has a function with the magic name __sleep. If so, that function is executed prior to any serialization. It can clean up the object and is supposed to return an array with the names of all variables of that object that should be serialized. If the method doesn’t return anything then NULL is serialized and E_NOTICE is issued.

__wakeup
Conversely, unserialize() checks for the presence of a function with the magic name __wakeup. If present, this function can reconstruct any resources that the object may have.

Example:
class Connection {
protected $link;
private $server, $username, $password, $db;

public function __construct($server, $username, $password, $db)
{
$this->server = $server;
$this->username = $username;
$this->password = $password;
$this->db = $db;
$this->connect();
}

private function connect()
{
$this->link = mysql_connect($this->server, $this->username, $this->password);
mysql_select_db($this->db, $this->link);
}

public function __sleep()
{
return array('server', 'username', 'password', 'db');
}

public function __wakeup()
{
$this->connect();
}
}

__tostring
The __toString method allows a class to decide how it will react when it is converted to a string.

Example
class Member
{
private $m_szEmail;
private $m_szUsername;

public function __construct($szUsername, $szEmail)
{
$this->m_szUsername = $szUsername;
$this->m_szEmail = $szEmail;
}
}

$pMember = new Member('Karl', 'karl@talkphp.com');

echo $pMember;

O/P is object.

Usually, most people would achieve this with code like:

echo $pMember->getUsername() . " (" . $pMember->getEmail() . ")";

However, what we can do is use the __toString() function to change the default behaviour of the object to string conversion. This would allow us to specify exactly
Add this method in your class

public function __toString()
{
return sprintf('%s (%s)', $this->m_szUsername, $this->m_szEmail);
}

__set() is run when writing data to inaccessible properties.

__get() is utilized for reading data from inaccessible properties.

__isset() is triggered by calling isset() or empty() on inaccessible properties.

__unset() is invoked when unset() is used on inaccessible properties.

__call() is triggered when invoking inaccessible methods in an object context.

__callStatic() is triggered when invoking inaccessible methods in a static context.

__invoke() this method is called when a script tries to call an object as a function.

__set_state() This static method is called for classes exported by var_export() since PHP 5.1.0.

The only parameter of this method is an array containing exported properties in the form array('property' => value, ...).

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PHP 5 OOPS concepts Key Words

Extends
In PHP a class a class can inherit methods, functions and members of other class by using the extends keyword in the declaration. In PHP it is not possible to inherit from multiple classes, a class can inherit from only one base class.

The class from which inheritance is done is called the parent class or base class and the class which inherits is called the child class.

Final
The final keyword prevents the child classes from overriding a method. This can be done by prefixing the method with the keyword final. If the complete class is being defined as final then that class cannot be extended.

Abstract
A new concept of abstract classes and methods has been introduced in PHP5. When a class is defined as abstract then it is not allowed to create the instance of that class. A class that contains at least one abstract method must also be abstract. The methods defined as abstract cannot define the implementation; they just declare the method’s signature.

When a child class is inheriting from an abstract parent class, then all the methods marked abstract in parent class declaration must also be additionally defined by the child class. These methods must be defined with the same or weaker access. This means that if an abstract method is declared as protected in the parent class then it must be declared either as protected or public in the child class.

Static
When class members or methods are declared as static then there is no need to instantiate that class. These members and methods are accessible without the instantiation of the class. If a member is declared as static then it cannot be accessed by an instantiated class object, but a method declared as static can be accessed by an instantiated class object.

The static declaration of a class must be after the visibility declaration (means that after the member or method has been declared as public, protected, or private).

The static method calls are resolved at compile time and static properties cannot be accessed through the object through the arrow operator (->).

Interfaces
Object interfaces allow the creation of a code which specifies that which method a class must implement, without having to define how these methods have to be handled.

Interfaces are defined in the same way as a class is defined. These interfaces are defined with the keyword “interface”. In the interface the contents of the methods do not have to be defined and all the methods declared in the interface must be declared as public.

Implementation of Interfaces
To implement an interface, the implements operator is used. The methods must be defined before implementation and all the methods in the interface must be implemented within a class.

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Introduction of SOAP Architecture

Simplified Object Access Protocol (SOAP) is a specification that enables applications to communicate with other applications. It provides a framework for connecting Web sites and applications to create Web services. These Web services link different sites and applications together to perform functions that the individual components or sites are not capable of. SOAP provides a mechanism by which each service can expose its features and communicate with other services. Using SOAP, one can link services offered by different systems together as components and use these components to build a complex information system application in a much shorter timeframe.

High-Level diagram of SOAP in a distributed system

Advantages of SOAP
1. SOAP is an open standard that is built upon open technologies such as XML and HTTP. It is not vendor-specific and therefore less intimidating to smaller players in the industry. As a result it is being accepted uniformly by the industry, thus improving its chances of being the de-facto standard for true distributed interoperability.
2. SOAP based distributed systems are loosely-coupled. As a result they are easier to maintain because they can be modified independently of other systems.
3. When used over HTTP protocol, SOAP packets can easily bypass firewalls if their content is not deemed malicious.

Disadvantages of SOAP
1. SOAP’s relied on HTTP for transport of XML data in the version 1.0 of its specification. HTTP requires a stateless request/response architecture that is not appropriate under all circumstances. While one can work around the state problem it requires additional coding.
2. All SOAP data is serialized and passed by value and currently there is no provision for passing data by reference. This could lead to synchronization problems if multiple copies of the same object are being passed at the same time.

SOAP Architecture

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Configure Virual host in Apache

Virtual hosting is a method for hosting multiple domain names on a computer using a single IP address. This allows one machine to share its resources, such as memory and processor cycles, to use its resources more efficiently.

One widely used application is shared web hosting. Shared web hosting prices are lower than a dedicated web server, because this allows many customers to be hosted on a single server.

Setting Up A Virtual Host in Apache
Setting up a virtual host in the Apache web server is not exactly a PHP topic, but many PHP developers use the Apache web server to test web pages on their development machine.

There is a lot of information around on how to do this, but the first time I tried it, I found the existing information to be more confusing than helpful. Hopefully, this page will simplify the process a bit. Please note that this information pertains to setting up a virtual host in Apache on a Windows machine for use as a local testing server.

Configuring Apache

The first file we'll need to edit is the Apache httpd.conf file. If you installed the Apache software using the download from the Apache web site, you should have a menu item that will open this file for editing. Click Start->Programs->Apache HTTP Server->Configure Apache Server->Edit the Apache httpd.conf Configuration File. If you don't have that start menu item, start your text editor and open the file. It will be in a sub-folder named conf of your Apache folder. For example, mine is here:

C:\Program Files\Apache Group\Apache\conf\httpd.conf

Notes for Apache Server Versions Since 2.2 Configuration

Note that Apache changed the preferred method for configuring the Apache server with the release of Apache 2.2. For versions beginning with 2.2, the peferred configuration is more modular. Setting up a virtual host as described here will still work with the newer versions, but to follow the modular approach, the editing of httpd.conf is only to uncomment (remove the # from the beginning of the following line:

#Include conf/extra/httpd-vhosts.conf

Everything else is entered in the file httpd-vhosts.conf, which will be located in the extra folder below the below the folder containing httpd.conf. As mentioned, the method described here will still work.
Security

Version 2.2 also changed some of the default security configuration parameters. To set things up the way you'll need them, you'll need to add the following block to either your httpd.conf file, just above the virtual hosts, or to your httpd-vhosts.conf file:

<Directory "C:\ My Sites ">
Order Deny,Allow
Allow from all
</Directory>

Simple Steps are:

1. Open the vhosts file in the apache folder and create a virtual path and the name which will be map the related folder and the server name for example

<VirtualHost 127.0.0.1>
DocumentRoot "C:\My Sites\Site1"
ServerName original
</VirtualHost>

<VirtualHost 127.0.0.1>
DocumentRoot "C:\My Sites\Site2"
ServerName testing
</VirtualHost>

2. Open 'hosts' file which is present in path "C:\WINNT\system32\drivers\etc\hosts"
add the server name to them. This will tell the apache that both the server
names should be responded For example

127.0.0.1 original
127.0.0.1 testing

Restart the apache server and your done

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