Tuesday, September 18, 2012

top core php interview questions and answers

If experienced Most be read two link (most of the interviewer asked those question and answer)


For starting /beginner  interview you can read all those interview questions and answers
1) What is PHP?
PHP is a web language based on scripts that allows developers to dynamically create generated web pages.
2) What does the initials of PHP stand for?
PHP means PHP: Hypertext Preprocessor.
3) Which programming language does PHP resemble to?
PHP syntax resembles Perl and C
4) What does PEAR stands for?
PEAR means “PHP Extension and Application Repository”. it extends PHP and provides a higher level of programming for web developers.
5) What is the actually used PHP version?
Version 5 is the actually used version of PHP.
6) How do you execute a PHP script from the command line?
Just use the PHP command line interface (CLI) and specify the file name of the script to be executed as follows:
?
1
php script.php
7) How to run the interactive PHP shell from the command line interface?
Just use the PHP CLI program with the option -a as follows:
?
1
php -a
8 What are the correct and the most two common way to start and finish a PHP block of code?
The two most  common ways to start and finish a PHP script are: <?php [   ---  PHP code---- ] ?> and <? [---  PHP code  ---] ?>
9) How can we display the output directly to the browser?
To be able to display the output directly to the browser, we have to use the special tags <?= and ?>.
10) What is the main difference between PHP 4 and PHP 5?
PHP 5 presents many additional OOP (Object Oriented Programming) features.
11) Is multiple inheritance supported in PHP?
PHP includes only single inheritance, it means that a class can be extended from only one single class using the keyword ‘extended’.
12) What is the meaning of a final class and a final method?
‘final’ is introduced in PHP5. Final class means that this class cannot be extended and a final method cannot be overrided.
13) How comparison of objects is done in PHP5?
We use the operator ‘==’ to test is two object are instanced from the same class and have same attributes and equal values. We can test if two object are refering to the same instance of the same class by the use of the identity operator ‘===’.
14) How can PHP and HTML interact?
It is possible to generate HTML through PHP scripts, and it is possible to pass informations from HTML to PHP.
15) What type of operation is needed when passing values through a form or an URL?
If we would like to pass values througn a form or an URL then we need to encode and to decode them using htmlspecialchars() and urlencode().
16) How can PHP and Javascript interact?
PHP and Javascript cannot directly interacts since PHP is a server side language and Javascript is a client side language. However we can exchange variables since PHP is able to generate Javascript code to be executed by the browser and it is possible to pass specific variables back to PHP via the URL.
17) What is needed to be able to use image function?
GD library is needed to be able execute image functions.
18) What is the use of the function ‘imagetypes()’?
imagetypes() gives the image format and types supported by the current version of GD-PHP.
19) What are the functions to be used to get the image’s properties (size, width and height)?
The functions are getimagesize() for size, imagesx() for width and imagesy() for height.
20) How failures in execution are handled with include() and require() functions?
If the function require() cannot access to the file then it ends with a fatal error. However, the include() function gives a warning and the PHP script continues to execute.
21) What is the main difference between require() and require_once()?
require() and require_once() perform the same task except that the second function checks if the PHP script is already included or not before executing it.
(same for include_once() and include())
22) How can I display text with a PHP script?
Two methods are possible:
?
1
2
3
4
<?php
echo "Method 1";
print "Method 2";
?>
23) How can we display information of a variable and readable by human with PHP?
To be able to display a human-readable result we use print_r().
24) How is it possible to set an infinite execution time for PHP script?
The set_time_limit(0) added at the beginning of a script sets to infinite the time of execution to not have the PHP error ‘maximum execution time exceeded’.It is also possible to specify this in the php.ini file.
 25) What does the PHP error ‘Parse error in PHP – unexpected T_variable at line x’ means?
This is a PHP syntax error expressing that a mistake at the line x stops parsing and executing the program.
26) What should we do to be able to export data into an Excel file?
The most common and used way is to get data into a format supported by Excel. For example, it is possible to write a .csv file, to choose for example comma as separator between fields and then to open the file with Excel.
27) What is the function file_get_contents() usefull for?
file_get_contents() lets reading a file and storing it in a string variable.
28) How can we connect to a MySQL database from a PHP script?
To be able to connect to a MySQL database, we must use mysql_connect() function as follows:
?
1
2
3
4
<?php
$database = mysql_connect("HOST", "USER_NAME", "PASSWORD");
mysql_select_db("DATABASE_NAME",$database);
?>
29) What is the function mysql_pconnect() usefull for?
mysql_pconnect() ensure a persistent connection to the database, it means that the connection do not close when the the PHP script ends.
30) How the result set of Mysql be handled in PHP?
The result set can be handled using mysql_fetch_array, mysql_fetch_assoc, mysql_fetch_object or mysql_fetch_row.
31) How is it possible to know the number of rows returned in result set?
The function mysql_num_rows() returns the number of rows in a result set.
32) Which function gives us the number of affected entries by a query?
mysql_affected_rows() return the number of entries affected by an SQL query.
33) What is the difference between mysql_fetch_object() and mysql_fetch_array()?
The mysql_fetch_object() function collects the first single matching record where mysql_fetch_array() collects all matching records from the table in an array.
34) How can we access the data sent through the URL with the GET method?
In order to access the data sent via the GET method, we you use $_GET array like this:
www.url.com?var=value
$variable = $_GET["var"]; this will now contain ‘value’
35) How can we access the data sent through the URL with the POST method?
To access the data sent this way, you use the $_POST array.
Imagine you have a form field called ‘var’ on the form, when the user clicks submit to the post form, you can then access the value like this:
$_POST["var"];
36) How can we check the value of a given variable is a number?
It is possible to use the dedicated function, is_numeric() to check whether it is a number or not.
37) How can we check the value of a given variable is alphanumeric?
It is possible to use the dedicated function, ctype_alpha() to check whether it is an alphanumeric value or not.
38) How do I check if a given variable is empty?
If we want to check whether a variable has a value or not, it is possible to use the empty() function.
39) What does the unlink() function means?
The unlink() function is dedicated for file system handling. It simply deletes the file given as entry.
40) What does the unset() function means?
The unset() function is dedicated for variable management. It will make a variable undefined.
The behavior of unset() inside of a function can vary depending on what type of variable you are attempting to destroy. 
41) How do I escape data before storing it into the database?
addslashes function enables us to escape data before storage into the database.
42) How is it possible to remove escape characters from a string?
The stripslashes function enables us to remove the escape characters before apostrophes in a string.
43) How can we automatically escape incoming data?
We have to enable the Magic quotes entry in the configuration file of PHP.
44) What does the function get_magic_quotes_gpc() means?
The function get_magic_quotes_gpc() tells us whether the magic quotes is switched on or no.
45) Is it possible to remove the HTML tags from data?
The strip_tags() function enables us to clean a string from the HTML tags.
46) what is the static variable in function useful for?
A static variable is defined within a function only the first time and its value can be modified during function calls as follows:
?
1
2
3
4
5
6
7
8
9
<?php
function testFunction() { static $testVariable = 1;
echo $testVariable;
$testVariable++;
}
testFunction();        //1
testFunction();        //2
testFunction();        //3
?>
47) How can we define a variable accessible in functions of a PHP script?
This feature is possible using the global keyword.
48) How is it possible to return a value from a function?
A function returns a value using the instruction ‘return $value;’.
49) What is the most convenient hashing method to be used to hash passwords?
It is preferable to use crypt() which natively supports several hashing algorithms or the function hash() which supports more variants than crypt() rather than using the common hashing algorithms such as md5, sha1 or sha256 because they are conceived to be fast. hence, hashing passwords with these algorithms can vulnerability.
50) Which cryptographic extension provide generation and verification of digital signatures?
The PHP-openssl extension provides several cryptographic operations including generation and verification of digital signatures.
51) How a constant is defined in a PHP script?
The define() directive lets us defining a constant as follows:
define (“ACONSTANT”, 123);
52) How can you pass a variable by reference?
To be able to pass a variable by reference, we use an ampersand in front of it, as follows $var1 = &$var2
53) Will a comparison of an integer 12 and a string “13″ work in PHP?
“13″ and 12 can be compared in PHP since it casts everything to the integer type.
54) How is it possible to cast types in PHP?
The name of the output type have to be specified in parentheses before the variable which is to be cast as follows:
* (int), (integer) – cast to integer
* (bool), (boolean) – cast to boolean
* (float), (double), (real) – cast to float
* (string) – cast to string
* (array) – cast to array
* (object) – cast to object
55) When a conditional statement is ended with an endif?
When the original if was followed by : and then the code block without braces.
56) How is the ternary conditional operator used in PHP?
It is composed of three expressions: a condition, and two operands describing what instruction should be performed when the specified condition is true or false as follows:
Expression_1 ? Expression_2 : Expression_3;
57) What is the function func_num_args() used for?
The function func_num_args() is used to give the number of parameters passed into a function.
58) If the variable $var1 is set to 10 and the $var2 is set to the character var1, what’s the value of $$var2?
$$var2 contains the value 10.
59) What does accessing a class via :: means?
:: is used to access static methods that do not require object initialization.
60) In PHP, objects are they passed by value or by reference?
In PHP, objects passed by value.
61) Are Parent constructors called implicitly inside a class constructor?
No, a parent constructor have to be called explicitly as follows:
parent::constructor($value)
62) What’s the difference between __sleep and __wakeup?
__sleep returns the array of all the variables that need to be saved, while __wakeup retrieves them.
63) What is faster?
1- Combining two variables as follows:
$variable1 = ‘Hello ‘;
$variable2 = ‘World’;
$variable3 = $variable1.$variable2;
Or
2- $variable3 = “$variable1$variable2″;
$variable3 will contain “Hello World”. The first code is faster than the second code especially for large large sets of data.
64) what is the definition of a session?
A session is a logical object enabling us to preserve temporary data across multiple PHP pages.
65) How to initiate a session in PHP?
The use of the function session_start() lets us activating a session.
66) How is it possible to propagate a session id?
It is possible to propagate a session id via cookies or URL parameters.
67) What is the meaning of a Persistent Cookie?
A persistent cookie is permanently stored in a cookie file on the browser’s computer. By default, cookies are temporary and are erased if we close the browser.
68) When sessions ends?
Sessions automatically ends when the PHP script finishs executing, but can be manually ended using the session_write_close().
69) What is the difference between session_unregister() and session_unset()?
The session_unregister() function unregister a global variable from the current session and the session_unset() function free all session variables.
70) What does $GLOBALS means?
$GLOBALS is associative array including references to all variables which are currently defined in the global scope of the script.
71) What does $_SERVER means?
$_SERVER is an array including information created by the web server such as paths, headers, and script locations.
72) What does $_FILES means?
$_FILES is an associative array composed of items sent to the current script via the HTTP POST method.
73) What is the difference between $_FILES['userfile']['name'] and $_FILES['userfile']['tmp_name']?
$_FILES['userfile']['name'] represents the original name of the file on the client machine,
$_FILES['userfile']['tmp_name'] represents the temporary filename of the file stored on the server.
74) How can we get the error when there is a problem to upload a file?
$_FILES['userfile']['error'] contains the error code associated with the uploaded file.
75) How can we change the maximum size of the files to be uploaded?
We can change the maximum size of files to be uploaded by changing upload_max_filesize in php.ini.
76) What does $_ENV means?
$_ENV is an associative array of variables sent to the current PHP script via the environment method.
77) What does $_COOKIE means?
$_COOKIE is an associative array of variables sent to the current PHP script using the HTTP Cookies.
78) What does the scope of variables means?
The scope of a variable is the context within which it is defined. For the most part all PHP variables only have a single scope. This single scope spans included and required files as well.
79) what the difference between the ‘BITWISE AND’ operator and the ‘LOGICAL AND’ operator?
$a and $b:    TRUE if both $a and $b are TRUE.
$a & $b:        Bits that are set in both $a and $b are set.
80) What are the two main string operators?
The first is the concatenation operator (‘.’), which returns the concatenation of its right and left arguments. The second is (‘.=’), which appends the argument on the right to the argument on the left.
81) What does the array operator ‘===’ means?
$a === $b TRUE if $a and $b have the same key/value pairs in the same order and of the same types.
82) What is the differences between $a != $b and $a !== $b?
!= means inequality (TRUE if $a is not equal to $b) and !== means non-identity (TRUE if $a is not identical to $b).
83) How can we determine whether a PHP variable is an instantiated object of a certain class?
To be able to verify whether a PHP variable is an instantiated object of a certain class we use instanceof.
84) What is the goto statement useful for?
The goto statement can be placed to enable jumping inside the PHP program. The target is pointed by a label followed by a colon, and the instruction is specified as a goto statement followed by the desired target label.
85) what is the difference between  Exception::getMessage and Exception::getLine ?
Exception::getMessage lets us getting the Exception message and Exception::getLine lets us getting the line in which the exception occurred.
86) What does the expression Exception::__toString means?
Exception::__toString gives the String representation of the exception.
87) How is it possible to parse a configuration file?
The function parse_ini_file() enables us to load in the ini file specified in filename, and returns the settings in it in an associative array.
88) How can we determine whether a variable is set?
The boolean function isset determines if a variable is set and is not NULL.
89) What is the difference between the functions strstr() and stristr()?
The string function strstr(string allString, string occ) returns part of allString from the first occurrence of occ to the end of allString. This function is case-sensitive. stristr() is identical to strstr() except that it is case insensitive.
90) what is the difference between for and foreach?
for is expressed as follows:
for (expr1; expr2; expr3)
statement
The first expression is executed once at the beginning. In each iteration, expr2 is evaluated. If it is TRUE, the loop continues and the statements inside for are executed. If it evaluates to FALSE, the execution of the loop ends. expr3 is tested at the end of each iteration.
However, foreach provides an easy way to iterate over arrays and it is only used with arrays and objects.
91) Is it possible to submit a form with a dedicated button?
It is possible to use the document.form.submit() function to submit the form. For example: <input type=button value=”SUBMIT” onClick=”document.form.submit()”>
92) What is the difference between ereg_replace() and eregi_replace()?
The function eregi_replace() is identical to the function ereg_replace() except that it ignores case distinction when matching alphabetic characters.
93) Is it possible to protect special characters in a query string?
Yes, we use the urlencode() function to be able to protect special characters.
94) What are the three classes of errors that can occur in PHP?
The three basic classes of errors are notices (non-critical), warnings (serious errors) and fatal errors (critical errors).
95) What is the difference between characters \034 and \x34?
\034 is octal 34 and \x34 is hex 34.
96) How can we pass the variable through the navigation between the pages?
It is possible to pass the variables between the PHP pages using sessions, cookies or hidden form fields.
97) Is it possible to extend the execution time of a php script?
The use of the set_time_limit(int seconds) enables us to extend the execution time of a php script. The default limit is 30 seconds.
98) Is it possible to destroy a cookie?
Yes, it is possible by setting the cookie with a past expiration time.
99) What is the default session time in php?
It depends on the server configuration or the relevant directives (session.gc_maxlifetime) in php.ini. Typically the default is 24 minutes (1440 seconds).
100) Is it possible to use COM component in PHP?
Yes, it’s possible to integrate (Distributed) Component Object Model components ((D)COM) in PHP scripts which is provided as a framework.

Mostly read two link (most of the interviewer asked those question and answer)



66 comments:

  1. I`m pleasure to read this article . i found lot of tricky question and answer.

    thank
    again

    ReplyDelete
  2. so much useful for me
    Thanks

    ReplyDelete
    Replies
    1. Hello @Sandeep,
      thanks for comment .if you have experienced you might be go through the last two link of this blog it must be help you for facing interview

      Delete
  3. thanks for your post its very useful..............

    ReplyDelete
    Replies
    1. Hi @hariharan thanks for your appreciation :)

      Delete
  4. Hi

    Thanks for basic question and answer

    please correct this as well

    40) What does the unset() function means?

    ReplyDelete
    Replies
    1. Hi Guru,

      Thanks for comments and thanks to point the mistake .............
      :)

      Delete
  5. Replies
    1. I am happy who body helpful my blog readers .........................:)

      Delete
  6. thanks :)...
    99) What is the default session time in php?
    The default session time in php is until closing of browser....
    i think this answer is wrong.......
    It depends on the server configuration or the relevant directives (session.gc_maxlifetime) in php.ini. Typically the default is 24 minutes (1440 seconds), but your webhost may have altered the default to something else.

    ReplyDelete
    Replies
    1. @Sarbaz i have updated your answer you are right...............thanks

      Delete
  7. Thank you very much,
    These Q&A session helped me to evaluate my knowledge in basic php & fresh up my knowledge in php & thanks once again

    ReplyDelete
  8. Thanku sir.. check out http://askxpert.com/php-interview-questions-and-answers

    ReplyDelete
  9. Informative article on responsive website design!!! With the expansion of mobile phones, most of us access internet from our mobile and other portable gadgets. Having responsive website for your business will help you to target customers widely. web designing course | Web designing classes in Chennai | website design in Chennai

    ReplyDelete
  10. Oracle DBA Training in Chennai
    Thanks for sharing this informative blog. I did Oracle DBA Certification in Greens Technology at Adyar. This is really useful for me to make a bright career..

    ReplyDelete
  11. Whatever we gathered information from the blogs, we should implement that in practically then only we can understand that exact thing clearly, but it’s no need to do it, because you have explained the concepts very well. It was crystal clear, keep sharing..
    Websphere Training in Chennai

    ReplyDelete
  12. Data warehousing Training in Chennai
    I am reading your post from the beginning, it was so interesting to read & I feel thanks to you for posting such a good blog, keep updates regularly..

    ReplyDelete
  13. Selenium Training in Chennai
    Wonderful blog.. Thanks for sharing informative blog.. its very useful to me..

    ReplyDelete
  14. Oracle Training in chennai
    Thanks for sharing such a great information..Its really nice and informative..

    ReplyDelete
  15. SAP Training in Chennai
    This post is really nice and informative. The explanation given is really comprehensive and informative..

    ReplyDelete
  16. This information is impressive..I am inspired with your post writing style & how continuously you describe this topic. After reading your post,thanks
    for taking the time to discuss this, I feel happy about it and I love learning more about this topic
    Android Training In Chennai In Chennai

    ReplyDelete
  17. Pretty article! I found some useful information in your blog, it was awesome to read,thanks for sharing this great content to my vision, keep sharing..
    Unix Training In Chennai

    ReplyDelete
  18. I found some useful information in your blog, it was awesome to read, thanks for sharing this great content to my vision, keep sharing..
    SalesForce Training in Chennai

    ReplyDelete
  19. There are lots of information about latest technology and how to get trained in them, like Best Hadoop Training In Chennai in Chennai have spread around the web, but this is a unique one according to me. The strategy you have updated here will make me to get trained in future technologies Hadoop Training in Chennai By the way you are running a great blog. Thanks for sharing this blogs..

    ReplyDelete
  20. This is really an awesome article. Thank you for sharing this.It is worth reading for everyone. Visit us:
    Oracle Training in Chennai

    ReplyDelete
  21. very nice blogs!!! i have to learning for lot of information for this sites...Sharing for wonderful information.Thanks for sharing this valuable information to our vision. You have posted a trust worthy blog keep sharing.
    Oracle DBA Training in Chennai

    ReplyDelete
  22. great article!!!!!This is very importent information for us.I like all content and information.I have read it.You know more about this please visit again.
    Oracle RAC Training in Chennai

    ReplyDelete
  23. Wonderful tips, very helpful well explained. Your post is definitely incredible. I will refer this to my friend.
    SalesForce Training in Chennai

    ReplyDelete
  24. I am reading your post from the beginning, it was so interesting to read & I feel thanks to you for posting such a good blog, keep updates regularly.
    Java Training in Chennai

    ReplyDelete
  25. Really awesome blog. Your blog is really useful for me. Thanks for sharing this informative blog. Keep update your blog.
    PHP Training in Chennai

    ReplyDelete
  26. Thanks for sharing this valuable information to our vision. You have posted a trust worthy blog keep sharing.Nice article i was really impressed by seeing this article, it was very interesting and it is very useful for me..
    Android Training in Chennai

    ReplyDelete
  27. Really awesome blog. Your blog is really useful for me. Thanks for sharing this informative blog. Keep update your blog.
    SAP Training in Chennai

    ReplyDelete
  28. Excellent information with unique content and it is very useful to know about the information based on blogs.
    Hadoop Training in Chennai

    ReplyDelete
  29. This information is impressive; I am inspired with your post writing style & how continuously you describe this topic. After reading your post, thanks for taking the time to discuss this, I feel happy about it and I love learning more about this topic..
    Selenium Training in Chennai | QTP Training in Chennai

    ReplyDelete
  30. Thanks for Information Oracle Apps Technical is a collection of a bunch of collected applications like accounts payables, purchasing, inventory, accounts receivables, human resources, order management, general ledger and fixed assets, etc which have its own functionality for serving the business
    Oracle Apps Training In Chennai

    ReplyDelete
  31. Oracle Training in chennai | Oracle D2K Training In chennai
    This information is impressive; I am inspired with your post writing style & how continuously you describe this topic. After reading your post, thanks for taking the time to discuss this, I feel happy about it and I love learning more about this topic..

    ReplyDelete
  32. This comment has been removed by the author.

    ReplyDelete
  33. Very informative post and great list of interview questions and answers you have shared here. Ecommerce Development Company Bangalore

    ReplyDelete
  34. Very informative post and great list of interview questions and answers you have shared here.
    datastage training in chennai

    ReplyDelete
  35. Very informative post and great list of interview questions and answers you have shared here.
    mongoDB training in chennai

    ReplyDelete
  36. • Need help with qtp? have a doubt in qtp? call me 8939925577 and refer software testing help website.
    oracle training in chennai

    ReplyDelete
  37. • Thank you for sharing this information and Very good looking blog.
    ios training in chennai

    ReplyDelete
  38. Thank you for your nice post.ERP Software company chennai For more details Call: +044 4283 5587.

    ReplyDelete
  39. Given so much info in it, These type of articles keeps the users interest in the website, and keep on sharing more ..Best Angularjs Training in Chennai|Angularjs Training in Chennai

    ReplyDelete
  40. Thank you for sharing the important information ..feeling good for getting the best information about PHP.
    Website Designing Company in Delhi | Website Designing Company in Rohini | Website Designing Company in Kirti Nagar

    ReplyDelete
  41. Thank you for sharing such an informative news with us. Keep on sharing Contents like this. You can also share this content on various sites like the Automation Associates LLC site.

    ReplyDelete
  42. Thank you for sharing this information. Come back again for more interesting stuff like this post. You can share this informative post in Social Media sites like the worldwide famous Facebook, the all-time favorite Twitter and the most interesting Google Plus site, business site LinkedIn and also to the Infographic site Pinterest to generate more traffic to your blog post.

    ReplyDelete
  43. I have analyzed your post. Excellent details you did here. I enjoyed reading your blog, and it is both instructional and enjoyable. Share this most interesting post in other sites like OS Business Opportunities, the innovative Asaim Japan site and also to the Jfissures site followed by Free Samples 411 and lastly to the sites like Johny Adams sites.

    ReplyDelete
  44. The post is very informative. It is a pleasure reading it. I have also bookmarked you for checking out new posts. You can also share this valuable content on other platforms such as Blogspot, the famous Wordpress site, the innovative Tumblr site and also the sites like Medium and the famous Live Journal site.

    ReplyDelete
  45. Thanks For Your valuable posting, it was very informative
    Schulungsangebote

    ReplyDelete
  46. The website is looking bit flashy and it catches the visitors eyes. A design is pretty simple .
    Stellenbörse

    ReplyDelete
  47. Your website content nice nice and interesting to observe.
    jobbörse Neunkirchen

    ReplyDelete
  48. The website is looking bit flashy and it catches the visitors eyes. A design is pretty simple .
    office 2016 professional plus 64 bit

    ReplyDelete
  49. Your website content nice nice and interesting to observe.
    ssd festplatte

    ReplyDelete