PHP Interview Questions and Answers – Part 5

81 How we load all classes that placed in different directory in one PHP File , means how to do auto load classes
by using spl_autoload_register(‘autoloader::funtion’);
Like below

class autoloader

public static function moduleautoloader($class)
$path = $_SERVER[‘DOCUMENT_ROOT’] . “/modules/{$class}.php”;
if (is_readable($path)) require $path;

public static function daoautoloader($class)
$path = $_SERVER[‘DOCUMENT_ROOT’] . “/dataobjects/{$class}.php”;
if (is_readable($path)) require $path;
public static function includesautoloader($class)
$path = $_SERVER[‘DOCUMENT_ROOT’] . “/includes/{$class}.php”;
if (is_readable($path)) require $path;

82 How many types of Inheritances used in PHP and how we achieve it
As far PHP concern it only support single Inheritance in scripting.
we can also use interface to achieve multiple inheritance.

83 PHP how to know user has read the email?
Using Disposition-Notification-To: in mailheader we can get read receipt.
Add the possibility to define a read receipt when sending an email.
It’s quite straightforward, just edit email.php, and add this at vars definitions:
var $readReceipt = null;
And then, at ‘createHeader’ function add:
if (!empty($this->readReceipt)) {
$this->__header .= ‘Disposition-Notification-To: ‘ . $this->__formatAddress($this->readReceipt) . $this->_newLine;

84 What are default session time and path?
default session time in PHP is 1440 seconds or 24 minutes
Default session save path id temporary folder /tmp

85 how to track user logged out or not? when user is idle ?
By checking the session variable exist or not while loading th page. As the session will exist longer as till browser closes. The default behaviour for sessions is to keep a session open indefinitely and only to expire a session when the browser is closed. This behaviour can be changed in the php.ini file by altering the line session.cookie_lifetime = 0 to a value in seconds. If you wanted the session to finish in 5 minutes you would set this to session.cookie_lifetime = 300 and restart your httpd server.

86 how to track no of user logged in ?
whenever a user logs in track the IP, userID etc..and store it in a DB with a active flag while log out or sesion expire make it inactive. At any time by counting the no: of active records we can get the no: of visitors.

87 in PHP for pdf which library used?
The PDF functions in PHP can create PDF files using the PDFlib library With version 6, PDFlib offers an object-oriented API for PHP 5 in addition to the function-oriented API for PHP 4. There is also the » Panda module. FPDF is a PHP class which allows to generate PDF files with pure PHP, that is to say without using the PDFlib library. F from FPDF stands for Free: you may use it for any kind of usage and modify it to suit your needs. FPDF requires no extension (except zlib to activate compression and GD for GIF support) and works with PHP4 and PHP5.

88 for image work which library?
we will need to compile PHP with the GD library of image functions for this to work. GD and PHP may also require other libraries, depending on which image formats you want to work with.

89 what is design pattern? singleton pattern?
A design pattern is a general reusable solution to a commonly occurring problem in software design.
The Singleton design pattern allows many parts of a program to share a single resource without having to work out the details of the sharing themselves.

90 what are magic methods?
9Magic methods are the members functions that is available to all the instance of class Magic methods always starts with “__”. Eg. __construct All magic methods needs to be declared as public To use magic method they should be defined within the class or program scope Various Magic Methods used in PHP 5 are: __construct() __destruct() __set() __get() __call() __toString() __sleep() __wakeup() __isset() __unset() __autoload() __clone()

91 what is magic quotes?
Magic Quotes is a process that automagically escapes ncoming data to the PHP script. It’s preferred to code with magic quotes off and to instead escape the data at runtime, as needed. This feature has been DEPRECATED as of PHP 5.3.0 and REMOVED as of PHP 6.0.0. Relying on this feature is highly discouraged.

92 what is cross site scripting? SQL injection?
Cross-site scripting (XSS) is a type of computer security vulnerability typically found in web applications which allow code injection by malicious web users into the web pages viewed by other users. Examples of such code include HTML code and client-side scripts. SQL injection is a code injection technique that exploits a security vulnerability occurring in the database layer of an application. The vulnerability is present when user input is either incorrectly filtered for string literal escape characters embedded in SQL statements or user input is not strongly typed and thereby unexpectedly executed

93 what is URL rewriting?
Using URL rewriting we can convert dynamic URl to static URL Static URLs are known to be better than Dynamic URLs because of a number of reasons 1. Static URLs typically Rank better in Search Engines. 2. Search Engines are known to index the content of dynamic pages a lot slower compared to static pages. 3. Static URLs are always more friendlier looking to the End Users. along with this we can use URL rewriting in adding variables [cookies] to the URL to handle the sessions.

94 what is the major php security hole? how to avoid?
1. Never include, require, or otherwise open a file with a filename based on user input, without thoroughly checking it first.
2. Be careful with eval() Placing user-inputted values into the eval() function can be extremely dangerous. You essentially give the malicious user the ability to execute any command he or she wishes!
3. Be careful when using register_globals = ON It was originally designed to make programming in PHP easier (and that it did), but misuse of it often led to security holes
4. Never run unescaped queries
5. For protected areas, use sessions or validate the login every time.
6. If you don’t want the file contents to be seen, give the file a .php extension.

95 whether PHP supports Microsoft SQL server ?
The SQL Server Driver for PHP v1.0 is designed to enable reliable, scalable integration with SQL Server for PHP applications deployed on the Windows platform. The Driver for PHP is a PHP 5 extension that allows the reading and writing of SQL Server data from within PHP scripts. using MSSQL or ODBC modules we can access Microsoft SQL server.

96 what is MVC? why its been used?
Model-view-controller (MVC) is an architectural pattern used in software engineering. Successful use of the pattern isolates business logic from user interface considerations, resulting in an application where it is easier to modify either the visual appearance of the application or the underlying business rules without affecting the other. In MVC, the model represents the information (the data) of the application; the view corresponds to elements of the user interface such as text, checkbox items, and so forth; and the controller manages the communication of data and the business rules used to manipulate the data to and from the model. WHY ITS NEEDED IS 1 Modular separation of function 2 Easier to maintain 3 View-Controller separation means:
A Tweaking design (HTML) without altering code B Web design staff can modify UI without understanding code

97 what is framework? how it works? what is advantage?
In general, a framework is a real or conceptual structure intended to serve as a support or guide for the building of something that expands the structure into something useful. Advantages : Consistent Programming Model Direct Support for Security Simplified Development Efforts Easy Application Deployment and Maintenance

98 what is CURL?
CURL means Client URL Library
curl is a command line tool for transferring files with URL syntax, supporting FTP, FTPS, HTTP, HTTPS, SCP, SFTP, TFTP, TELNET, DICT, LDAP, LDAPS and FILE. curl supports SSL certificates, HTTP POST, HTTP PUT, FTP uploading, HTTP form based upload, proxies, cookies, user+password authentication (Basic, Digest, NTLM, Negotiate, kerberos…), file transfer resume, proxy tunneling and a busload of other useful tricks.
CURL allows you to connect and communicate to many different types of servers with many different types of protocols. libcurl currently supports the http, https, ftp, gopher, telnet, dict, file, and ldap protocols. libcurl also supports HTTPS certificates, HTTP POST, HTTP PUT, FTP uploading (this can also be done with PHP’s ftp extension), HTTP form based upload, proxies, cookies, and user+password authentication.

99 what is PDO ?
The PDO ( PHP Data Objects ) extension defines a lightweight, consistent interface for accessing databases in PHP. if you are using the PDO API, you could switch the database server you used, from say PgSQL to MySQL, and only need to make minor changes to your PHP code.
While PDO has its advantages, such as a clean, simple, portable API but its maindisadvantage is that it doesn’t allow you to use all of the advanced features that are available in the latest versions of MySQL server. For example, PDO does not allow you to use MySQL’s support for Multiple Statements.
Just need to use below code for connect mysql using PDO
try {
$dbh = new PDO(“mysql:host=$hostname;dbname=databasename”, $username, $password);
$sql = “SELECT * FROM employee”;
foreach ($dbh->query($sql) as $row)
print $row[’employee_name’] .’ – ‘. $row[’employee_age’] ;
catch(PDOException $e)
echo $e->getMessage();

100 What is PHP’s mysqli Extension?
The mysqli extension, or as it is sometimes known, the MySQL improved extension, was developed to take advantage of new features found in MySQL systems versions 4.1.3 and newer. The mysqli extension is included with PHP versions 5 and later.
The mysqli extension has a number of benefits, the key enhancements over the mysql extension being:
=>Object-oriented interface
=>Support for Prepared Statements
=>Support for Multiple Statements
=>Support for Transactions
=>Enhanced debugging capabilities
=>Embedded server support

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