125 Top Php Job Interview Questions and Answers [PHP] Questions

PHP Interview Questions with Answers:-

1. Define what is PHP?
The PHP Hypertext Preprocessor is a programming language that allows web developers to create dynamic content that interacts with databases. PHP is basically used for developing web-based software applications.

2. Define what Is a Session?

A session is a logical object created by the PHP engine to allow you to preserve data across subsequent HTTP requests.
There is only one session object available to your PHP scripts at any time. Data saved to the session by a script can be retrieved by the same script or another script when requested from the same visitor.
Sessions are commonly used to store temporary data to allow multiple PHP pages to offer a complete functional transaction for the same visitor.

3. Define 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.

4. Define How can we know the number of days between two given dates using PHP?
Simple arithmetic:
$date1 = date(‘Y-m-d’);
$date2 = ‘2006-07-01’;
$days = (strtotime() – strtotime()) / (60 * 60 * 24);
echo “Number of days since ‘2006-07-01’: $days”;

5. Define How can we repair a MySQL table?
The syntax for repairing a MySQL table is:

REPAIR TABLE table name
REPAIR TABLE tablename QUICK
REPAIR TABLE tablename EXTENDED
This command will repair the table specified.
If QUICK is given, MySQL will do a repair of only the index tree.
If EXTENDED is given, it will create index row by row.

6. Define what is the difference between $message and $$message?
Answer 1:
$message is a simple variable whereas $$message is a reference variable. Example:
$user = ‘bob’
is equivalent to
$holder = ‘user’;
$$holder = ‘bob’;
Anwser 2:
They are both variables. But $message is a variable with a fixed name. $$message is a variable whose name is stored in $message. For example, if $message contains “var”, $$message is the same as $var.

7. Define what Is a Persistent Cookie?
A persistent cookie is a cookie which is stored in a cookie file permanently on the browser’s computer. By default, cookies are created as temporary cookies which stored only in the browser’s memory. When the browser is closed, temporary cookies will be erased. You should decide when to use temporary cookies and when to use persistent cookies based on their differences:

Temporary cookies can not be used for tracking long-term information.
Persistent cookies can be used for tracking long-term information.
Temporary cookies are safer because no programs other than the browser can access them.
Persistent cookies are less secure because users can open cookie files to see the cookie values.

8. Define what does a special set of tags do in PHP?
The output is displayed directly to the browser.

9. Define How do you define a constant?
Via define() directive, like define (“MYCONSTANT”, 100);
Define what are the differences between require and include, include_once?
Answer 1:
require_once() and include_once() are both the functions to include and evaluate the specified file only once. If the specified file is included previous to the present call occurrence, it will not be done again.
But require() and include() will do it as many times they are asked to do.
Anwser 2:
The include_once() statement includes and evaluates the specified file during the execution of the script. This is a behavior similar to the include() statement, with the only difference being that if the code from a file has already been included, it will not be included again. The major difference between include() and require() is that in failure include() produces a warning message whereas require() produces a fatal error.
Answer 3:
All three are used to an include file into the current page.
If the file is not present, require(), calls a fatal error, while in include() does not.
The include_once() statement includes and evaluates the specified file during the execution of the script. This is a behavior similar to the include() statement, with the only difference being that if the code from a file has already been included, it will not be included again. It does do not call a fatal error if file not exists. require_once() does the same as include_once(), but it calls a fatal error if file not exists.
Answer 4:
The file will not be included more than once. If we want to include a file once only and further calling of the file will be ignored when we have to use the PHP function
include_once(). This will prevent problems with function redefinitions, variable value reassignments, etc.

10. Define what is meant by urlencode and urldecode?
Answer 1:
urlencode() returns the URL encoded version of the given string. URL coding converts special characters into % signs followed by two hex digits. For example:
urlencode(“10.00%”) will return “10%2E00%25”. URL encoded strings are safe to be used as part of URLs.
urldecode() returns the URL decoded version of the given string.
Answer 2:
string urlencode(str) – Returns the URL encoded version of the input string. String values to be used in URL query string need to be URL encoded. In the URL encoded version:
Alphanumeric characters are maintained as is.
Space characters are converted to “+” characters.
Other non-alphanumeric characters are converted “%” followed by two hex digits representing the converted character.
string urldecode(str) – Returns the original string of the input URL encoded string.
For example:
$discount =”10.00%”;
$url = “http://domain.com/submit.php?disc=”.urlencode($discount);
echo $url;
You will get “http://domain.com/submit.php?disc=10%2E00%25”.

11. Define How To Get the Uploaded File Information in the Receiving Script?
Once the Web server received the uploaded file, it will call the PHP script specified in the form action attribute to process them. This receiving PHP script can get the uploaded file information through the predefined array called $_FILES. Uploaded file information is organized in $_FILES as a two-dimensional array as:
· $_FILES[$fieldName][‘name’] – The Original file name on the browser system.
· $_FILES[$fieldName][‘type’] – The file type determined by the browser.
· $_FILES[$fieldName][‘size’] – The Number of bytes of the file content.
· $_FILES[$fieldName][‘tmp_name’] – The temporary filename of the file in which
the uploaded file was stored on the server.
· $_FILES[$fieldName][‘error’] – The error code associated with this file upload.
The $fieldName is the name used in the <INPUT TYPE=FILE, NAME=fieldName>

12. Define what is the difference between mysql_fetch_object and mysql_fetch_array?
MySQL fetch object will collect first single matching record where mysql_fetch_array will collect all matching records from the table in an array

13. Define How can I execute a PHP script using command line?
Just run the PHP CLI (Command Line Interface) program and provide the PHP script file name as the command line argument. For example, “php myScript.php”, assuming “php” is the command to invoke the CLI program.
Be aware that if your PHP script was written for the Web CGI interface, it may not execute properly in command line environment.

14. Define what are the different tables present in MySQL? Which type of table is generated when we are creating a table in the following syntax: create table employee(no
int(2), name varchar(10))?
Total 5 types of tables we can create

MyISAM
Heap
Merge
INNO DB
ISAM

15. Define How To Create a Table?
If you want to create a table, you can run the CREATE TABLE statement as define How in the following sample script:

Remember that mysql_query() returns TRUE/FALSE on CREATE statements. If you run this script, you will get something like this:
Table fyi_links created.

16. Define How can we encrypt the username and password using PHP?
Answer1
You can encrypt a password with the following Mysql>SET PASSWORD=PASSWORD(“Password”);
Answer2
You can use the MySQL PASSWORD() function to encrypt username and password.
For example,
INSERT into user (password, …) VALUES (PASSWORD($password”)), …);

17. Define How do you pass a variable by value?
Just like in C++, put an ampersand in front of it, like $a = &$b

Define what IS THE FUNCTIONALITY OF THE FUNCTIONS STRSTR() AND STRISTR()?
string strstr ( string haystack, string needle ) returns part of haystack string from the first occurrence of needle to the end of haystack. This function is case-sensitive.
stristr() is identical to strstr() except that it is case insensitive.

18. When are you supposed to use endif to end the conditional statement?
When the original if was followed by: and then the code block without braces.

19. Define How can we send mail using JavaScript?
No. There is no way to send emails directly using JavaScript.
But you can use JavaScript to execute a client-side email program send the email using the “mailto” code. Here is an example:
function function(form)
{
tdata=document.myform.tbox1.value;
location=”mailto:[email protected]?subject=…”;
return true;
}

20. Define what is the functionality of the function strstr and stricter?
strstr() returns part of a given string from the first occurrence of a given substring to the end of the string. For example, strstr(“[email protected]”,”@”) will return “@example.com”.
stristr() is identical to strstr() except that it is case insensitive.

21. Define what is the difference between ereg_replace() and eregi_replace()?
eregi_replace() function is identical to ereg_replace() except that it ignores case distinction when matching alphabetic characters.

22. Define How do I find out the number of parameters passed into function9. ?
func_num_args() function returns the number of parameters passed in.

23. Write a select query that will be displayed the duplicated site name and Define How many times it is duplicated?
SELECT site name, COUNT(*) AS NumOccurrences
FROM tbl_sites
GROUP BY site name HAVING COUNT(*) > 1

24. Define How To Protect Special Characters in Query String?
If you want to include special characters like spaces in the query string, you need to protect them by applying the urlencode() translation function. The script below sDefine Hows Define How to use urlencode():

<?php
print(“<html>”);
print(“<p>Please click the links below”
.” to submit comments about FYICenter.com:</p>”);
$comment = ‘I want to say: “It’s a good site! :->”‘;
$comment = urlencode($comment);
print(“<p>”
.”<a href=”processing_forms.php?name=Guest&comment=$comment”>”
.”It’s an excellent site!</a></p>”);
$comment = ‘This visitor said: “It’s an average site! :-(“‘;
$comment = urlencode($comment);
print(“<p>”
.'<a href=”processing_forms.php?’.$comment.’”>’
.”It’s an average site.</a></p>”);
print(“</html>”);
?>

25. Are objects passed by value or by reference?
Everything is passed by value.

26. Define what are the differences between DROP a table and TRUNCATE a table?
DROP TABLE table_name – This will delete the table and its data.
TRUNCATE TABLE table_name – This will delete the data of the table, but not the table definition.

27. Define what are the differences between getting and POST methods in form submitting, give the case where we can use GET and we can use POST methods?
Answer 1:
When we submit a form, which has the GET method it displays a pair of name/value used in the form at the address bar of the browser preceded by URL. Post method doesn’t display these values.
Answer 2:
When you want to send short or small data, not containing ASCII characters, then you can use GET” Method. But for long data sending, say more than 100 characters you can use the POST method.
Once the most important difference is when you are sending the form with getting method. You can see the output which you are sending in the address bar. Whereas if you send the form with POST” method then the user can not see that information.

28. Define what are the Different Types of Errors in PHP?
Here are three basic types of runtime errors in PHP:
1. Notices: These are trivial, non-critical errors that PHP encounters while executing a script – for example, accessing a variable that has not yet been defined. By default, such errors are not displayed to the user at all – although you can change this default behavior.
2. Warnings: These are more serious errors – for example, attempting to include() a file which does not exist. By default, these errors are displayed to the user, but they do not result in script termination.
3. Fatal errors: These are critical errors – for example, instantiating an object of a nonexistent class, or calling a non-existent function. These errors cause the immediate termination of the script, and PHP’s default behavior is to display them to the user when they take place.
Internally, these variations are represented by twelve different error types.

29. Define what’s the special meaning of __sleep and __wakeup?
__sleep returns the array of all the variables that need to be saved, while __wakeup retrieves them.

30. Define How can we submit a form without a submit button?
If you don’t want to use the Submit button to submit a form, you can use normal hyperlinks to submit a form. But you need to use some JavaScript code in the URL of the link.
For example:
<a href=”javascript: document.myform.submit();”>Submit Me</a>
Why doesn’t the following code print the newline properly? <?php $str = ‘Hello,
there.define How are you? thanks for visiting epicenter’; print $str; ?>
Because inside the single quotes then the character is not interpreted as newline, just as a
sequence of two characters – and n.

31. Would you initialize your strings with single quotes or double quotes?
Since the data inside the single-quoted string is not parsed for variable substitution, it’s always a better idea speed-wise to initialize a string with single quotes, unless you specifically need variable substitution.

32. Define what is the difference between the functions unlink and unset?
unlink() is a function for file system handling. It will simply delete the file in context.
unset() is a function for variable management. It will make a variable undefined.

33. Define How come the code works but doesn’t for a two-dimensional array of mine?
Any time you have an array with more than one dimension, complex parsing syntax is required. print “Contents: {$arr[1][2]}” would’ve worked.

34. Define How can we register the variables into a session?
session_register($session_var);
$_SESSION[‘var’] = ‘value’;

35. Define what is the difference between characters 23 and x23?
The first one is octal 23, the second is hex 23.

36. Define How can we submit a form without a submit button?
We can use a simple JavaScript code linked to an event trigger of any form field. In the JavaScript code, we can call the document.form.submit() function to submit the form. For example: <input type=button value=”Save” onClick=”document.form.submit()”>

37. Define How can we create a database using PHP and MySQL?
We can create a MySQL database with the use of mysql_create_db($databaseName) to create a database.

38. Define How many ways we can retrieve the data in the result set of MySQL using PHP?
As individual objects so single record or as a set of arrays.

39. Define what’s the output of the ucwords function in this example?
$formatted = words(“FYICENTER IS COLLECTION OF INTERVIEW QUESTIONS”);
print $formatted;
Define what will be printed is FYICENTER IS COLLECTION OF INTERVIEW QUESTIONS.
ucwords() makes every first letter of every word capital, but it does not lower-case anything else. To avoid this, and get a properly formatted string, it’s worth using strtolower() first.

40. Define what’s the difference between htmlentities() and htmlspecialchars()?
htmlspecialchars only takes care of <, >, single quote ‘, double quote ” an ampersand.
htmlentities translates all occurrences of character sequences that have a different meaning in HTML.

41. Define what are the different functions in sorting an array?
Sorting functions in PHP:
asort()
arsort()
ksort()
krsort()
uksort()
sort()
natsort()
rsort()

42. Define How can we know the count/number of elements of an array?
2 ways:
a) sizeof($array) – This function is an alias of count()
b) count($urarray) – This function returns the number of elements in an array.
Interestingly if you just pass a simple var instead of an array, count() will return 1.

43. Define How many ways we can pass the variable through the navigation between the pages?
At least 3 ways:
1. Put the variable into session on the first page, and get it back from the session in the next page.
2. Put the variable into cookie in the first page, and get it back from the cookie in the next page.
3. Put the variable into a hidden form field, and get it back from the form in the next page.

44. Define what is the maximum length of a table name, a database name, or a field name in MySQL?

Database name: 64 characters
Table name: 64 characters
Column name: 64 characters

45. Define How many values can the SET function of MySQL take?
MySQL SET function can take zero or more values, but at the maximum, it can take 64 values.

46. Define what are the other commands to know the structure of a table using MySQL commands except EXPLAIN command?
DESCRIBE table_name;
Define How can we find the number of rows in a table using MySQL?
Use this for MySQL
SELECT COUNT(*) FROM table_name;

47. Define what’s the difference between md5(), crc32() and sha1() crypto on PHP?
The major difference is the length of the hash generated. CRC32 is, evidently, 32 bits, while sha1() returns a 128 bit value, and md5() returns a 160 bit value. This is important when avoiding collisions.

48. Define How can we find the number of rows in a result set using PHP?
Here is Define How can you find the number of rows in a result set in PHP:
$result = mysql_query($any_valid_sql, $database_link);
$num_rows = mysql_num_rows($result);
echo “$num_rows rows found”;

49. Define How many ways we can we find the current date using MySQL?

SELECT CURDATE();
SELECT CURRENT_DATE();
SELECT CURTIME();
SELECT CURRENT_TIME();

50. Give the syntax of GRANT commands?
The generic syntax for GRANT is as following GRANT [rights] on [database] TO [username@hostname] IDENTIFIED BY [password] Now rights can be:
a) ALL privileges
b) Combination of CREATE, DROP, SELECT, INSERT, UPDATE, and DELETE, etc.
We can grant rights on all database by using *.* or some specific database by database.*
or a specific table by database.table_name.

51. Define what is the value for this auto incremented field user_pri_id?
In both conditions, the value of this auto incremented field user_pri_id is 2346.

52. Define what is the difference between CHAR and VARCHAR data types?
CHAR is a fixed length data type. CHAR(n) will take n characters of storage even if you enter less than n characters to that column. For example, “Hello!” will be stored as “Hello! ” in the CHAR(10) column.
VARCHAR is a variable length data type. VARCHAR(n) will take only the required storage for the actual number of characters entered to that column. For example, “Hello!” will be stored as “Hello!” in VARCHAR(10) column.

53. Define How can we encrypt and decrypt a data present in a MySQL table using MySQL?
AES_ENCRYPT() and AES_DECRYPT()

54. Will comparison of string “10” and integer 11 work in PHP?
Yes, internally PHP will cast everything to the integer type, so numbers 10 and 11 will be compared.

55. Define what is the functionality of MD5 function in PHP?
string md5(string)
It calculates the MD5 hash of a string. The hash is a 32-character hexadecimal number.

56. Define How can I load data from a text file into a table?
The MySQL provides a LOAD DATA INFILE command. You can load data from a file.
Great tool but you need to make sure that:
a) Data must be delimited
b) Data fields must match table columns correctly

57. Define How can we know the number of days between two given dates using MySQL?
Use DATEDIFF()
SELECT DATEDIFF(NOW(),’2006-07-01′);

58. Define How can we change the name of a column of a table?
This will change the name of the column:
ALTER TABLE table_name CHANGE old_colm_name new_colm_name

59. Define How can we change the data type of a column of a table?
This will change the data type of a column:
ALTER TABLE table_name CHANGE colm_name same_colm_name [new data type]

60. Define what is the difference between GROUP BY and ORDER BY in SQL?
To sort a result, use an ORDER BY clause.
The most general way to satisfy a GROUP BY clause is to scan the whole table and create a new temporary table where all rows from each group are consecutive, and then
use this temporary table to discover groups and apply aggregate functions (if any).
ORDER BY [col1],[col2],…[coln]; Tells DBMS according to Define what columns it should sort the result. If two rows will have the same value in col1 it will try to sort them according to col2 and so on.
GROUP BY [col1],[col2],…[coln]; Tells DBMS to group (aggregate) results with the same value of column col1. You can use COUNT(col1), SUM(col1), AVG(col1) with it, if you want to count all items in group, sum all values or view average.

PHP Questions pdf free download::

61. Define what is meant by MIME?
Answer 1:
MIME is Multipurpose Internet Mail Extensions is an Internet standard for the format of e-mail. Define However browsers also uses the MIME standard to transmit files. MIME has a header which is added to the beginning of the data. When a browser sees such header it defines Hows the data as it would be a file (for example image)
Some examples of MIME types:
audio/x-ms-wmp
image/png
application/x-shockwave-flash
Answer 2:
Multipurpose Internet Mail Extensions.
WWW’s ability to recognize and handle files of different types is largely dependent on the use of the MIME (Multipurpose Internet Mail Extensions) standard. The standard provides for a system of registration of file types with information about the applications needed to process them. This information is incorporated into Web server and browser software and enables the automatic recognition and display of registered file types.

62. Define How can we know that a session is started or not?
A session starts by session_start() function.
This session_start() is always declared in header portion. it always declares first. then we write session_register().

63. Define what are the differences between mysql_fetch_array(), mysql_fetch_object(), mysql_fetch_row()?
mysql_fetch_array() -> Fetch a result row as a combination of associative array and regular array.
mysql_fetch_object() -> Fetch a result row as an object.
mysql_fetch_row() -> Fetch a result set as a regular array().

64. Define what are the MySQL database files stored in system ?

Data is stored in name.myd
The table structure is stored in name.frm
The index is stored in name.myi

65. Define what is the difference between PHP4 and PHP5?

PHP4 cannot support oops concepts and Zend engine 1 is used.
PHP5 supports oops concepts and Zend engine 2 is used.
Error supporting is increased in PHP5.
XML and SQLite will is increased in PHP5.

66. Can we use include(abc.PHP) two times in a PHP page makeit.PHP”?
Yes, we can include that many times we want, but here are some things to make sure of:
(including abc.PHP, the file names are case-sensitive)
there shouldn’t be any duplicate function names, means there should not be functions or classes or variables with the same name in abc.PHP and makeit.php

67. Define what are the differences between mysql_fetch_array(), mysql_fetch_object(), mysql_fetch_row()?
mysql_fetch_array – Fetch a result row as an associative array and a numeric array.
mysql_fetch_object – Returns an object with properties that correspond to the fetched row and moves the internal data pointer ahead. Returns an object with properties that correspond to the fetched row, or FALSE if there are no more rows mysql_fetch_row() – Fetches one row of data from the result associated with the specified
result identifier. The row is returned as an array. Each result column is stored in an array offset, starting at offset 0.

68. Define what is meant by nl2br()?
nl2br() inserts an HTML tag
before all newline characters n in a string.
echo nl2br(“God bless n you”);
output:
god bless
you

69. Define How can we encrypt and decrypt a data presented in a table using MySQL?
You can use functions: AES_ENCRYPT() and AES_DECRYPT() like:
AES_ENCRYPT(str, key_str)
AES_DECRYPT(crypt_str, key_str)

70. Define How can I retrieve values from one database server and store them in other database server using PHP?
For this purpose, you can first read the data from one server into session variables. Then connect to other server and simply insert the data into the database.

71. IN Define How MANY WAYS WE CAN RETRIEVE DATA IN THE RESULT SET OF MYSQL USING PHP?

mysql_fetch_array – Fetch a result row as an associative array, a numeric array, or both
mysql_fetch_assoc – Fetch a result row as an associative array
mysql_fetch_object – Fetch a result row as an object
mysql_fetch_row —- Get a result row as an enumerated array

72. Define what are the functions for IMAP?

imap_body – Read the message body
imap_check – Check current mailbox
imap_delete – Mark a message for deletion from current mailbox
imap_mail – Send an email message

73. Define what are encryption functions in PHP?

CRYPT()
MD5()

74. Define 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

75. Define what is the functionality of the function htmlentities?
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.

76. Define How can we get the properties (size, type, width, height) of an image using php image functions?

To know the image size use getimagesize() function
To know the image width use images() function
To know the image height use images() function

77. Define How can we increase the execution time of a PHP script?
By the use of void set_time_limit(in seconds)
Set the number of seconds a script is allowed to run. If this is reached, the script returns a fatal error. The default limit is 30 seconds or, if it exists, the max_execution_time value defined in the php.ini. If seconds is set to zero, no time limit is imposed.
When called, set_time_limit() restarts the timeout counter from zero. In other words, if the timeout is the default 30 seconds, and 25 seconds into script execution a call such as set_time_limit(20) is made, the script will run for a total of 45 seconds before timing out.

78. Define How CAN WE TAKE A BACKUP OF A MYSQL TABLE AND Define How CAN WE RESTORE IT?
Create a full backup of your database: shell> mysqldump tab=/path/to/some/dir opt db_name
Or: shell> mysqlhotcopy db_name /path/to/some/dir
The full backup file is just a set of SQL statements, so restoring it is very easy:
shell> MySQL “.”Executed”;

79. Define what TYPES OF IMAGES THAT PHP SUPPORTS?
Using image types() function to find out Define what types of images are supported in your PHP engine.
image types() – Returns the image types supported.
This function returns a bit-field corresponding to the image formats supported by the version of GD linked into PHP. The following bits are returned, IMG_GIF | IMG_JPG |IMG_PNG | IMG_WBMP | IMG_XPM.
CHECK IF A VARIABLE IS AN INTEGER IN JAVASCRIPT
var myValue =9.8;
if(parseInt(myValue)== myValue)
alert(‘Integer’);
else
alert(‘Not an integer’);
Tools used for drawing ER diagrams.
Case Studio
Smart Draw

80. Define How can I know that a variable is a number or not using a JavaScript?
Answer 1:
bool is_numeric( mixed var)
Returns TRUE if var is a number or a numeric string, FALSE otherwise.

81. Define How can we submit a form without a submit button?
Trigger the JavaScript code on any event ( like onSelect of the drop-down list box, focus, etc ) document.myform.submit(); This will submit the form.

82. Define How many ways can we get the value of current session id?
session_id() returns the session id for the current session.

83. Define How can we destroy the cookie?
Set the cookie with a past expiration time.

84. Define what are the current versions of Apache, PHP, and MySQL?
Apache 2.2.17
Php 5.3.3 – this is a newer version which introduced many oop properties to PHP like a namespace. But in practice, everyone uses 5.2.
Mysql 5.1.52 – supports triggers, stored procedures

85. Define 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 thereby reducing maintenance costs. OO
programming is also considered to be better at modeling the real world that 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.

86. Define what is the use of friend function?
Friend functions:
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.
class my linkage
{
private:
my linkage * prev;
my linkage * next;
protected:
friend void set_prev(my linkage* L, my linkage* N);
void set_next(my linkage* L);
public:
my linkage * success();
my linkage * pred();
my linkage();
};
void my linkage::set_next(my linkage* L) { next = L; }
void set_prev(my linkage * L, my linkage * N ) { N->prev = L; }
Friends in other classes
It is possible to specify a member function of another class as a friend as follows:
class C
{
friend int B::f1();
};
class B
{
int f1();
};
It is also possible to specify all the functions in another class as friends, by specifying the
entire class as a friend.
class A
{
friend class B;
};
Friend functions allow binary operators to be defined which combine private data in a pair of objects. This is particularly powerful when using the operator overloading features of C++. We will return to it when we look at overloading.

87. Define How can we get second of the current time using date function?
$second = date(“s”);

88. Define what is the maximum size of a file that can be uploaded using PHP and Define How can we change this?
You can change the maximum size of a file set upload_max_filesize variable in the php.ini file

89. Define what are the advantages of stored procedures, triggers, indexes?
A stored procedure is a set of SQL commands that can be compiled and stored in the server. Once this has been done, clients don’t need to keep re-issuing the entire query but can refer to the stored procedure. This provides better overall performance because the query has to be parsed only once, and less information needs to be sent between the server and the client. You can also raise the conceptual level by having libraries of functions in the server. Define, However, stored procedures, of course, to increase the load on the database server system, as more of the work is done on the server side and less on the client (application) side. Triggers will also be implemented.
A trigger is effectively a type of stored procedure, one that is invoked when a particular event occurs. For example, you can install a stored procedure that is triggered each time a record is deleted from a transaction table and that stored procedure automatically deletes the corresponding customer from a customer table when all his transactions are deleted.
Indexes are used to find rows with specific column values quickly. Without an index, MySQL must begin with the first row and then read through the entire table to find the relevant rows. The larger the table, the more this costs. If the table has an index for the columns in question,
MySQL can quickly determine the position to seek to in the middle of the data file without having to look at all the data. If a table has 1,000 rows, this is at least 100 times faster than reading sequentially. If you need to access most of the rows, it is faster to read sequentially, because this minimizes disk seeks.

90. Define what is the maximum size of a database in MySQL?
If the operating system or filesystem places a limit on the number of files in a directory, MySQL is bound by that constraint. The efficiency of the operating system in handling large numbers of files in a directory can place a practical limit on the number of tables in a database. If the time required to open a file in the directory increases significantly as the number of files increases, database performance can be adversely affected.
The amount of available disk space limits the number of tables.
MySQL 3.22 had a 4GB (4 gigabytes) limit on table size. With the MyISAM storage engine in MySQL 3.23, the maximum table size was increased to 65536 terabytes (2567
– 1 byte). With this larger allowed table size, the maximum effective table size for MySQL databases is usually determined by operating system constraints on file sizes, not by MySQL internal limits.
The InnoDB storage engine maintains InnoDB tables within a tablespace that can be created from several files. This allows a table to exceed the maximum individual file size. The tablespace can include raw disk partitions, which allows extremely large tables. The maximum tablespace size is 64TB.
The following table lists some examples of operating system file-size limits. This is only a rough guide and is not intended to be definitive. For the most up-to-date information, be sure to check the documentation specific to your operating system.
Operating System File-size Limit
Linux 2.2-Intel 32-bit 2GB (LFS: 4GB)
Linux 2.4+ (using ext3 filesystem) 4TB
Solaris 9/10 16TB
NetWare w/NSS filesystem 8TB
Win32 w/ FAT/FAT32 2GB/4GB
Win32 w/ NTFS 2TB (possibly larger)
MacOS X w/ HFS+ 2TB

91. Explain normalization concept?
The normalization process involves getting our data to conform to three progressive normal forms, and a higher level of normalization cannot be achieved until the previous levels have been achieved (there are actually five normal forms, but the last two are mainly academic and will not be discussed).
First Normal Form:
The First Normal Form (or 1NF) involves the removal of redundant data from horizontal rows. We want to ensure that there is no duplication of data in a given row and that every column stores the least amount of information possible (making the field atomic).
Second Normal Form:
Where the First Normal Form deals with redundancy of data across a horizontal row, Second Normal Form (or 2NF) deals with redundancy of data in vertical columns. As
stated earlier, the normal forms are progressive, so to achieve Second Normal Form, your tables must already be in First Normal Form.
Third Normal Form:
I have a confession to make; I do not often use the Third Normal Form. In Third Normal Form we are looking for data in our tables that is not fully dependant on the primary key but dependant on another value in the table

92. Define what type of inheritance that PHP supports?
In PHP an extended class is always dependent on a single base class, that is, multiple inheritances is not supported. Classes are extended using the keyword ‘extends’.

93. Define How can increase the performance of MySQL select query?
We can use LIMIT to stop MySql for further search in the table after we have received our required no. of records, also we can use LEFT JOIN or RIGHT JOIN instead of full join in cases we have related data in two or more tables.

94. Define How can we change the name of a column of a table?
MySQL query to rename table: RENAME TABLE tbl_name TO new_tbl_name or, ALTER TABLE tableName CHANGE OldName newName.

95. Define what are the different ways to login to a remote server? Explain the means, advantages, and disadvantages?
There are at least 3 ways to login to a remote server:
Use ssh or telnet if you concern with security
You can also use log in to log in to a remote server.
Please give a regular expression (preferably Perl/PREG style), which can be used to identify the URL from within an HTML link tag.
Try this: /href=”([^”]*)”/i

96. Define How can I use the COM components in PHP?
The COM class provides a framework to integrate (D)COM components into your PHP scripts.
string COM::COM( string module_name [, string server_name [, int codepage]]) – COM class constructor.
Parameters:
module_name: name or class-id of the requested component.
server_name: name of the DCOM server from which the component should be fetched. If NULL, localhost is assumed. To allow DCOM com, allow_dcom has to be set to TRUE
in php.ini.
codepage – specifies the codepage that is used to convert PHP-strings to Unicode-strings and vice versa. Possible values are CP_ACP, CP_MACCP, CP_OEMCP, CP_SYMBOL,
CP_THREAD_ACP, CP_UTF7, and CP_UTF8.
Usage:
$word->Visible = 1; //open an empty document
$word->Documents->Add(); //do some weird stuff
$word->Selection->TypeText(“This is a test…”);
$word->Documents[1]->SaveAs(“Useless test.doc”); //closing word
$word->Quit(); //free the object
$word->Release();
$word = null;

97. Define How many ways we can give the output to a browser?

HTML output
PHP, ASP, JSP, Servlet Function
Script Language output Function
Different Type of embedded Package to output to a browser

98. Define what is the default session time in php and Define How can I change it?
The default session time in php is until the closing of the browser

99. Define what is the difference between Reply-to and Return-path in the headers of a mail function?
Reply-to: Reply-to is where to delivery the reply of the mail.
Return-path: Return path is when there is a mail delivery failure occurs then where to delivery the failure notification.

100. Define How To Turn On the Session Support?
The session support can be turned on automatically at the site level, or manually in each PHP page script:

Turning on session support automatically at the site level: Set session.auto_start = 1 in php.ini.
Turning on session support manually in each page script: Call session_start() function.

101. Explain the ternary conditional operator in PHP?
Expression preceding the ? is evaluated, if it’s true, then the expression preceding the: is executed, otherwise, the expression following: is executed.

102. Define what’s the difference between include and require?
It’s Define How they handle failures. If the file is not found by require(), it will cause a fatal error and halt the execution of the script. If the file is not found by include(), a warning will be issued, but execution will continue.

103. Define How many ways can we get the value of current session id?
session_id() returns the session id for the current session.

104. Define How can we destroy the cookie?
Set the cookie in past.

105. Define How To Read the Entire File into a Single String?
If you have a file, and you want to read the entire file into a single string, you can use the file_get_contents() function. It opens the specified file, reads all characters in the file, and returns them in a single string. Here is a PHP script example on Define How to
file_get_contents():
<?php
$file = file_get_contents(“/windows/system32/drivers/etc/services”);
print(“Size of the file: “.strlen($file).”n”);
?>
This script will print:
Size of the file: 7116

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