PHP Interview Quesition & Answer2

What are the features and advantages of object-oriented programming?

One of the main advantages of OO programming is its ease of modification; objects can easily be modified and added to a system there by reducing maintenance costs. OO programming is also considered to be better at modeling the real world than is procedural programming. It allows for more complicated and flexible interactions. OO systems are also easier for non-technical personnel to understand and easier for them to participate in the maintenance and enhancement of a system because it appeals to natural human cognition patterns.
For some systems, an OO approach can speed development time since many objects are standard across systems and can be reused. Components that manage dates, shipping, shopping carts, etc. can be purchased and easily modified for a specific system

What are the differences between procedure-oriented languages and object-oriented languages?

There are lot of difference between procedure language and object oriented like below
1>Procedure language easy for new developer but complex to understand whole software as compare to object oriented model
2>In Procedure language it is difficult to use design pattern mvc , Singleton pattern etc but in OOP you we able to develop design pattern
3>IN OOP language we able to ree use code like Inheritance ,polymorphism etc but this type of thing not available in procedure language on that our Fonda use COPY and PASTE .

What is the use of friend function?

Sometimes a function is best shared among a number of different classes. Such functions can be declared either as member functions of one class or as global functions. In either case they can be set to be friends of other classes, by using a friend specifier in the class that is admitting them. Such functions can use all attributes of the class
which names them as a friend, as if they were themselves members of that class.
A friend declaration is essentially a prototype for a member function, but instead of requiring an implementation with the name of that class attached by the double colon syntax, a global function or member function of another class provides the match.

What are the differences between public, private, protected, static, transient, final and volatile?

Public: Public declared items can be accessed everywhere.
Protected: Protected limits access to inherited and parent classes (and to the class that defines the item).
Private: Private limits visibility only to the class that defines the item.
Static: A static variable exists only in a local function scope, but it does not lose its value when program execution leaves this scope.
Final: Final keyword prevents child classes from overriding a method by prefixing the definition with final. If the class itself is being defined final then it cannot be extended. transient: A transient variable is a variable that may not be serialized.
volatile: a variable that might be concurrently modified by multiple threads should be declared volatile. Variables declared to be volatile will not be optimized by the compiler because their value can change at any time.

What is the functionality of the function strstr and stristr?

strstr Returns part of string from the first occurrence of needle(sub string that we finding out ) to the end of string.
$email= ‘sonialouder@gmail.com’;
$domain = strstr($email, ‘@’);
echo $domain; // prints @gmail.com
here @ is the needle
stristr is case-insensitive means able not able to diffrenciate between a and A

What are the differences between PHP 3 and PHP 4 and PHP 5?

There are lot of difference among these three version of php
1>Php3 is oldest version after that php4 came and current version is php5 (php5.3) where php6 have to come
2>Difference mean oldest version have less functionality as compare to new one like php5 have all OOPs concept now where as php3 was pure procedural language constructive like C
In PHP5 1. Implementation of exceptions and exception handling
2. Type hinting which allows you to force the type of a specific argument
3. Overloading of methods through the __call function
4. Full constructors and destructors etc through a __constuctor and __destructor function
5. __autoload function for dynamically including certain include files depending on the class you are trying to create.
6 Finality : can now use the final keyword to indicate that a method cannot be overridden by a child. You can also declare an entire class as final which prevents it from having any children at all.
7 Interfaces & Abstract Classes
8 Passed by Reference :
9 An __clone method if you really want to duplicate an object

What is the functionality of the function htmlentities?

Convert all applicable characters to HTML entities This function is identical to htmlspecialchars() in all ways, except with htmlentities(), all characters which have HTML character entity equivalents are translated into these entities.

How can we get second of the current time using date function?

<?php $second = date(“s”); ?>

How can we convert the time zones using PHP?

<?php By using date_default_timezone_get and
date_default_timezone_set function on PHP 5.1.0

// Discover what 8am in Tokyo relates to on the East Coast of the US

// Set the default timezone to Tokyo time:
date_default_timezone_set(‘Asia/Tokyo’);

// Now generate the timestamp for that particular timezone, on Jan 1st, 2000
$stamp = mktime(8, 0, 0, 1, 1, 2000);

// Now set the timezone back to US/Eastern
date_default_timezone_set(‘US/Eastern’);

// Output the date in a standard format (RFC1123), this will print:
// Fri, 31 Dec 1999 18:00:00 EST
echo ‘

‘, date(DATE_RFC1123, $stamp) ,’

‘;?>

What is meant by urlencode and urldocode?

URLencode returns a string in which all non-alphanumeric characters
except -_. have been replaced with a percent (%)
sign followed by two hex digits and spaces encoded as plus (+)
signs. It is encoded the same way that the posted data from a WWW form
is encoded, that is the same way as in
application/x-www-form-urlencoded media type.

urldecode decodes any %##
encoding in the given string.

What is the difference between the functions unlink and unset?

unlink() deletes the given file from the file system.
unset() makes a variable undefined.

How can we register the variables into a session?

$_SESSION[‘name’] = “girdhari”;

How can we get the properties (size, type, width, height) of an image using PHP image functions?

To know the Image type use exif_imagetype () function
To know the Image size use getimagesize () function
To know the image width use imagesx () function
To know the image height use imagesy() function

How can we get the browser properties using PHP?

By using $_SERVER[‘HTTP_USER_AGENT’] variable.

What is the maximum size of a file that can be uploaded using PHP and how can we change this?

By default the maximum size is 2MB. and we can change the following
setup at php.iniupload_max_filesize = 2M

How can we increase the execution time of a PHP script?

by changing the following setup at php.inimax_execution_time = 30; Maximum execution time of each script, in seconds

How can we take a backup of a MySQL table and how can we restore it. ?

To backup: BACKUP TABLE tbl_name[,tbl_name…] TO
‘/path/to/backup/directory’
RESTORE TABLE tbl_name[,tbl_name…] FROM ‘/path/to/backup/directory’mysqldump: Dumping Table Structure and DataUtility to dump a database or a collection of database for backup or for transferring the data to another SQL server (not necessarily a MySQL server). The dump will contain SQL statements to create the table and/or populate the table. -t, no-create-info
Don’t write table creation information (the CREATE TABLE statement).
-d, no-data
Don’t write any row information for the table. This is very useful if
you just want to get a dump of the structure for a table!

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