PHP Interview Questions -8

PHP Interview Questions -8
1. What is the actually used PHP version?

Version 5 is the actually used version of PHP.

2. 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.

3.Which programming language does PHP resemble to?

HP syntax resembles Perl and C

4.What does the initials of PHP stand for?

PHP means PHP: Hypertext Preprocessor.

5. How to run the interactive PHP shell from the command line interface?

ust use the PHP CLI program with the option -a as follows:

php -a

6.How do you execute a PHP script from the command line?

ust use the PHP command line interface (CLI) and specify the file name of the script to be executed as follows:

php script.php

7.Which of the following functions allows you to store session data in a database?

session_set_save_handler() to override

8.Which of the following types can be used as an array key

Object

9.Which of the following functions can be used to sort an array by its keys in descending order?

krsort

10.What will the following script output?

Nothing

11.In how many ways we can retrieve the data in the result set of MySQL using PHP?

You can do it by 4 Ways

1. mysql_fetch_row.
2. mysql_fetch_array
3. mysql_fetch_object
4. mysql_fetch_assoc

12. How can we create a database using PHP and MySQL?

We can create MySQL Database with the use of mysql_create_db(“Database Name”).

13. How can we submit a form without a submit button?

The main idea behind this is to use Java script submit() function in order to submit the form without explicitly clicking any submit button. You can attach the document.formname.submit() method to onclick, onchange events of different inputs and perform the form submission. you
can even built a timer function where you can automatically submit the form after xx seconds once the loading is done (can be seen in online test sites).

14. Can we use include (”abc.PHP”) two times in a PHP page “makeit.PHP”?

Yes we can use include() more than one time in any page though it is not a very good practice.

15. Functions in IMAP, POP3 AND LDAP? How can we encrypt and decrypt a data present in a MySQL table using MySQL?

AES_ENCRYPT () and AES_DECRYPT ()

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

$second = date(”s”);

17. What is PHP?

PHP is a web language based on scripts that allows developers to dynamically create generated web pages.

18. What does the initials of PHP stand for?

PHP means PHP: Hypertext Preprocessor.

19. Which programming language does PHP resemble to?

PHP syntax resembles Perl and C

20. 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.

21.  What is the actually used PHP version?

Version 5 is the actually used version of PHP.

22. 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:

php script.php

23. How to run the interactive PHP shell from the command line interface?

Just use the PHP CLI program with the option -a as follows:

php -a

24. 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  ---] ?>

25. 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 ?>.

26. What is the main difference between PHP 4 and PHP 5?

PHP 5 presents many additional OOP (Object Oriented Programming) features.

27. 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.

28. 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).

29. 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.

30. 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.

31. 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.

32. What does the expression Exception::__toString means?

Exception::__toString gives the String representation of the exception.

33. 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.

34. How can we determine whether a variable is set?

The boolean function isset determines if a variable is set and is not NULL.

35.  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.

36. 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.

37. What does $_SERVER means?

$_SERVER is an array including information created by the web server such as paths, headers, and script locations.

38. What does $_FILES means?

$_FILES is an associative array composed of items sent to the current script via the HTTP POST method.

39. 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.

40. 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.

41. 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.

42. What does $_ENV means?

$_ENV is an associative array of variables sent to the current PHP script via the environment method.

43. What does $_COOKIE means?

$_COOKIE is an associative array of variables sent to the current PHP script using the HTTP Cookies.

44. 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.

45. 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.

46. 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.

47. How a constant is defined in a PHP script?

The define() directive lets us defining a constant as follows:

define (“ACONSTANT”, 123);

48. 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

49. 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.

50. 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

51. When a conditional statement is ended with an endif?

When the original if was followed by : and then the code block without braces.

52. 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;

53. 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.

54. 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.

55. What does accessing a class via :: means?

is used to access static methods that do not require object initialization.

56. In PHP, objects are they passed by value or by reference?

In PHP, objects passed by value.

57. How do I escape data before storing it into the database?

addslashes function enables us to escape data before storage into the database.

58.  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.

59. How can we automatically escape incoming data?

We have to enable the Magic quotes entry in the configuration file of PHP.

60. 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.

61. Is it possible to remove the HTML tags from data?

The strip_tags() function enables us to clean a string from the HTML tags.

62. 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:

<?php
function testFunction() { static $testVariable = 1;
echo $testVariable;
$testVariable++;
}
testFunction();        //1
testFunction();        //2
testFunction();        //3
?>

63.  How can we define a variable accessible in functions of a PHP script?

This feature is possible using the global keyword.

64. How is it possible to return a value from a function?

A function returns a value using the instruction ‘return $value;’.

65. 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.

66. 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.

67. 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.

68. 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.

69. 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.

70. 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’

71. 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"];

72. 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.

73. 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.

74. 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.

75. What does the unlink() function means?

The unlink() function is dedicated for file system handling. It simply deletes the file given as entry.

76. What does the unset() function means?

The unlink() function is dedicated for variable management. It will make a variable undefined.

77. 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())

78. How can I display text with a PHP script?

Two methods are possible:

<?php
echo "Method 1"
print "Method 2"
?>

79. 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().

80. 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.

81. 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.

82.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.

83. What is the function file_get_contents() usefull for?

file_get_contents() lets reading a file and storing it in a string variable.

84.  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:

<?php
$database = mysql_connect("HOST", "USER_NAME", "PASSWORD");
mysql_select_db("DATABASE_NAME",$database);
?>
85. 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.

86. 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.

87. 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’.

88. 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.

89. 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 referring to the same instance of the same class by the use of the identity operator ‘===’.

90.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.

91. 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().

92. 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.

93. What is needed to be able to use image function?

GD library is needed to be able execute image functions.

94. What is the use of the function ‘imagetypes()’?

imagetypes() gives the image format and types supported by the current version of GD-PHP.

95. 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.

96. 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.

97.What is the difference between htmlentities() and htmlspecialchars()?

htmlspecialchars() – Convert some special characters to HTML entities (Only the most widely used) htmlentities() – Convert ALL special characters to HTML entities

98. for image work which library?

You 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.

99.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.

100.what is magic quotes?

Magic Quotes is a process that automagically escapes incoming 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.

101.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.

102.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

103.how to increase session time in PHP ?

In php.ini by setting session.gc_maxlifetime and session.cookie_lifetime values
we can change the session time in PHP.  

104.using CSS can we have a scroll to table?

No table won't support scrolling of its data. but we can do another workaround like placing a table
in a DIV  layer and setting the DIV css property to overflow:auto will do the trick.

105.Difference b/w OOPS concept in php4 and PHP5 ?

version 4’s object-oriented functionality was rather hobbled. Although the very basic premises of objectoriented programming (OOP) were offered in version 4, several deficiencies existed, including: • An unorthodox object-referencing methodology • No means for setting the scope (public, private, protected, abstract) of fields and methods • No standard convention for naming constructors • Absence of object destructors • Lack of an object-cloning feature • Lack of support for interfaces

106. What is the difference between characters \034 and \x34?

\034 is octal 34 and \x34 is hex 34.

107.Is it possible to destroy a cookie?

Yes, it is possible by setting the cookie with a past expiration time.

108.What is the default session time in php?

The default session time in php is until closing of browser

109.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.

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