PHP Top Interview Questions and Answers

PHP Interview Questions and Answers 

Questions 1 :  Who is the father of PHP ?

Answers : Rasmus Lerdorf is known as the father of PHP.

Questions 2 : What is the difference between $name and $$name?

Answers :  $name is variable where as $$name is reference variable like $name=sonia and $$name=singh so $sonia value is singh.

Questions 3 :  How can we submit a form without a submit button?

Answer  :  Java script submit() function is used for submit form without submit button on click call document.formname.submit()

Questions 4 :  In how many ways we can retrieve the data in the result set of MySQL using PHP?
Answer :  We can do it by 4 Ways
 1. mysql_fetch_row. ,
 2. mysql_fetch_array ,
 3. mysql_fetch_object
 4. mysql_fetch_assoc

Questions 5 :  What is the difference between mysql_fetch_object and mysql_fetch_array?

Answers :  mysql_fetch_object() is similar tomysql_fetch_array(), with one difference - an object is returned, instead of an array. Indirectly, that means that you can only access the data by the field names, and not by their offsets (numbers are illegal property names).

Questions 6:  How can we extract string "pcds.co.in " from a string "http://info@pcds.co.in using regular expression of PHP?

Answers :  preg_match("/^http:\/\/.+@(.+)$/","http://info@pcds.co.in",$matches); echo $matches[1];

Questions 7 :  What are the differences between Get and post methods.

Answers :   There are some defference between GET and POST method 1. GET Method have some limit like only 2Kb data able to send for request But in POST method unlimited data can we send 2. when we use GET method requested data show in url but Not in POST method so POST method is good for send sensetive request

Questions 8 :  How can we create a database using PHP and MySQL?

Answers : We can create MySQL database with the use of mysql_create_db("Database Name")

Questions 9 : What are the differences between require and include?

Answers :  Both include and require used to include a file but when included file not found Include send Warning where as Require send Fatal Error .

Questions 10 :  Can we use include ("xyz.PHP") two times in a PHP page "index.PHP"?

Answers :  Yes we can use include("xyz.php") more than one time in any page. but it create a prob when xyz.php file contain some funtions declaration then error will come for already declared function in this file else not a prob like if you want to show same content two time in page then must incude it two time not a prob

Questions 11: What are the different tables(Engine) present in MySQL, which one is default

Answers :  Following tables (Storage Engine) we can create

1. MyISAM(The default storage engine IN MYSQL Each MyISAM table is stored on disk in three files. The files have names that begin with the table name and have an extension to indicate the file type. An .frm file stores the table format. The data file has an .MYD (MYData) extension. The index file has an .MYI (MYIndex) extension. )
2. InnoDB(InnoDB is a transaction-safe (ACID compliant) storage engine for MySQL that has commit, rollback, and crash-recovery capabilities to protect user data.)
3. Merge
4. Heap (MEMORY)(The MEMORY storage engine creates tables with contents that are stored in memory. Formerly, these were known as HEAP tables. MEMORY is the preferred term, although HEAP remains supported for backward compatibility. )
5. BDB (BerkeleyDB)(Sleepycat Software has provided MySQL with the Berkeley DB transactional storage engine. This storage engine typically is called BDB for short. BDB tables may have a greater chance of surviving crashes and are also capable of COMMIT and ROLLBACK operations on transactions)
6. EXAMPLE 
7. FEDERATED (It is a storage engine that accesses data in tables of remote databases rather than in local tables. )
8. ARCHIVE (The ARCHIVE storage engine is used for storing large amounts of data without indexes in a very small footprint. )
9. CSV (The CSV storage engine stores data in text files using comma-separated values format.)
10. BLACKHOLE (The BLACKHOLE storage engine acts as a "black hole" that accepts data but throws it away and does not store it. Retrievals always return an empty result)

Questions 12:  What is use of header() function in php ?

Answers : The header() function sends a raw HTTP header to a client.We can use herder() function for redirection of pages. It is important to notice that header() must be called before any actual output is seen..

Questions 13: How can I execute a PHP script using command line?

Answers : Just run the PHP CLI (Command Line Interface) program and provide the PHP script file name as the command line argument.

Questions 14:  Suppose your Zend engine supports the mode Then how can u configure your PHP Zend engine to support mode ?

Answers :  In php.ini file: set short_open_tag=on to make PHP support

Questions : 15 What is meant by nl2br()?

Answers :  Inserts HTML line breaks (<BR/>) before all newlines in a string

Questions 16 : What is htaccess? Why do we use this and Where?

Answers :  .htaccess files are configuration files of Apache Server which provide a way to make configuration changes on a per-directory basis. A file, containing one or more configuration directives, is placed in a particular document directory, and the directives apply to that directory, and all subdirectories thereof.

Questions 17: How we get IP address of client, previous reference page etc ?Questions : 18 How we get IP address of client, previous reference page etc ?

Answers :  By using $_SERVER['REMOTE_ADDR'],$_SERVER['HTTP_REFERER'] etc.

Questions 18:  What are the reasons for selecting lamp (Linux, apache, MySQL, PHP) instead of combination of other software programs, servers and operating systems?

Answers :  All of those are open source resource. Security of Linux is very very more than windows. Apache is a better server that IIS both in functionality and security. MySQL is world most popular open source database. PHP is more faster that asp or any other scripting language.

Questions 19: How can we encrypt and decrypt a data present in a MySQL table using MySQL?

Answers  :  AES_ENCRYPT () and AES_DECRYPT ()

Questions 20 : What are the features and advantages of object-oriented programming?

Answers :  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

Questions 21:  What are the differences between procedure-oriented languages and object-oriented languages?

Answers :  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

Questions 22:  What is the use of friend function?

Answers : 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.

Questions 23:  What is the functionality of the function strstr and stristr?

Answers :  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

Questions 24:  How can we convert the time zones using PHP?
Answer :  By using date_default_timezone_get and 
date_default_timezone_set function on PHP 5.1.0

<?php
// 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 '<p>', date(DATE_RFC1123, $stamp) ,'</p>';?>

';?>

Questions 25:  What is meant by urlencode and urldocode?

Answer : 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.

Questions 26: What is the difference between the functions unlink and unset?
Answer :  unlink() deletes the given file from the file system.
                 unset() makes a variable undefined.

Questions 27: What is the difference between ereg_replace() and eregi_replace()?

Answer :  eregi_replace() function is identical to ereg_replace() except that this ignores case distinction when matching alphabetic characters.eregi_replace() function is identical to ereg_replace() except that this ignores case distinction when matching alphabetic characters.\

Questions 28:  How can I know that a variable is a number or not using a JavaScript?

Answer :  bool is_numeric ( mixed var) Returns TRUE if var is a number or a numeric string, FALSE otherwise.or use isNaN(mixed var)The isNaN() function is used to check if a value is not a number.

PHP Top Interview Questions and Answers