PHP Interview questions 2

1) How we load all classes that placed in different directory in one PHP File , means how to do auto load classes

Ans :      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;

}

}

spl_autoload_register('autoloader::includesautoloader');

spl_autoload_register('autoloader::daoautoloader');

spl_autoload_register('autoloader::moduleautoloader');

2) How many types of Inheritances used in PHP and how we achieve it

Ans :      As far PHP concern it only support single Inheritance in scripting.

we can also use interface to achieve multiple inheritance.

                 

3)          PHP how to know user has read the email?

Ans :      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;

}

4) What are default session time and path?

Ans :      default session time in PHP is 1440 seconds or 24 minutes

Default session save path id temporary folder /tmp

5) how to track user logged out or not? when user is idle ?

Ans : 85                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.

6) What is the difference between char and varchar data types?

Ans :      Set char to occupy n bytes and it will take n bytes even if u r storing a value of n-m bytes

Set varchar to occupy n bytes and it will take only the required space and will not use the n bytes

eg. name char(15) will waste 10 bytes if we store 'romharshan', if each char takes a byte eg. name varchar(15) will just use 5 bytes if we store 'romharshan', if each char takes a byte. rest 10 bytes will be free.

7) What is the functionality of md5 function in PHP?

Ans :      Calculate the md5 hash of a string. The hash is a 32-character hexadecimal number. I use it to generate keys which I use to identify users etc. If I add random no techniques to it the md5 generated now will be totally different for the same string I am using.

8) How can I load data from a text file into a table?

Ans :      you can use LOAD DATA INFILE file_name; syntax to load data from a text file. but you have to make sure thata) data is delimited

b) columns and data matched correctly

9) How can we know the number of days between two given dates using MySQL?

Ans :      SELECT DATEDIFF("2007-03-07","2005-01-01");

                 

10) How can we know the number of days between two given dates using PHP?

Ans :      $date1 = date("Y-m-d");

$date2 = "2006-08-15";

$days = (strtotime($date1) - strtotime($date2)) / (60 * 60 * 24);