100 REAL TIME PHP Interview Questions And Answers

PHP Interview Questions And Answers :-

PHP Interview Questions And Answers

PHP Interview Questions And Answers

1)What is PHP?

2)How a constant is defined in a PHP script?

3)What are the Difference Between strstr() and stristr()?

4)Differences between Get and post methods in PHP?

5)How do I find out the number of parameters passed into function. ?

6)What is urlencode and urldecode?

7)How to increase the execution time of a php script?

8)Difference between htmlentities() and htmlspecialchars()?

9)What is the difference between $message and $$message?

10)How To Get the Uploaded File Information in the Receiving Script?

11)What is difference between Array combine() and Array merge()?

12)What is Implode() Function in PHP?

13)what Explode() Function in PHP?

14)What does a special set of tags do in PHP?

15)What is the difference between md5(),crc32() and sha1() in PHP?

16)What are the differences between require() and include()?

17)What are the differences between require_once(), include_once?

18)What is session in php?

19)What is default session time in php?

20)What is Cookie and How to Create a Cookie in php?

21)How can you destroy or Delete a Cookie?

22)Difference between Persistent Cookie and Temporary cookie?

23)Difference Between Cookies and Sessions in php?

24)How to connet mysql database with PHP ?

25)What is the function mysql_pconnect() usefull for?

26)Different Types of Tables in Mysql?

27)What is the Difference between INNODB and MYISAM?

28) What is the difference between mysql_fetch_object() and mysql_fetch_array()?

29)What are the differences between DROP a table and TRUNCATE a table?

30)What is the maximum length of a table name, a database name, or a field name in MySQL?

31)What is the difference between CHAR and VARCHAR data types?

32)How can we know that a session is started or not?

33)What are the differences between GET and POST methods in form submitting, give the case where we can use get and we can use post methods?

34)Who is the father of php and explain the changes in php versions?

35)How can we submit from without a submit button?

36)How many ways we can retrieve the date in result set of mysql Using php?

37)What is the difference between $message and $$message?

38)What are the differences between require and include, include_once?

39)What are the different tables present in mysql?

40)How can I execute a php script using command line?

41)What is meant by nl2br()?

42)What are the current versions of apache, php, and mysql?

43)What are the reasons for selecting lamp (Linux, apache, mysql, php) instead of combination of other software programs, servers and operating systems?

44)How can we encrypt and decrypt a data present in a mysql table using mysql?

45)How can we encrypt the username and password using php?

46)What are the different types of errors in php?

47)What is the functionality of the function htmlentities?

48)What is meant by urlencode and urldocode?

49)What is the difference between the functions unlink and unset?

50)How can we register the variables into a session?

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

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

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

You can change maximum size of a file set upload_max_filesize variable in php.ini file.

53)How can we increase the execution time of a php script?

Set max_execution_time variable in php.ini file to your desired time in second.

54)How can we take a backup of a mysql table and how can we restore it.?

Create a full backup of your database: shell> mysqldump tab=/path/to/some/diropt 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”;

55)How many ways can we get the value of current session id?

session_id() function returns the session id for the current session.

56)How can we destroy the session, how can we unset the variable of a session?


57)How can we destroy the cookie?

Set same the cookie in past

58)What is the difference between ereg_replace() and eregi_replace()?

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.

59)How can we know the count/number of elements of an array?

2 ways
a) sizeof($urarray) This function is an alias of count()
b) count($urarray)
interestingly if u just pass a simple var instead of a an array it will return 1.

60)What is the maximum length of a table name, database name, and fieldname in mysql?

Database name- 64
Table name -64 Fieldname-64

61)How many values can the SET function of mysql takes?

Mysql set can take zero or more values but at the maximum it can take 64 values

62)What is 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 gigabyte) limit on table size. With the MyISAM storage engine in MySQL 3.23, the maximum table size was increased to 65536 terabytes (2567 — 1 bytes). 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

63)What is meant by MIME?

Multipurpose Internet Mail Extensions.
WWW ability to recognise 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.

64)What is meant by PEAR in php?

PEAR is short for “PHP Extension and Application Repository” and is pronounced just like the fruit. The purpose of PEAR is to provide:
A structured library of open-sourced code for PHP users
A system for code distribution and package maintenance
A standard style for code written in PHP
The PHP Foundation Classes (PFC),
The PHP Extension Community Library (PECL),
A web site, mailing lists and download mirrors to support the PHP/PEAR community
PEAR is a community-driven project with the PEAR Group as the governing body. The project has been founded by Stig S. Bakken in 1999 and quite a lot of people have joined the project since then.

65)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, a numeric array, or both.
mysql_fetch_object ( resource result )
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.

66)What is the difference between include and require?

If you require a file and it cannot be found, the script will terminate with a fatal error. If you use include then you will get an error but the script will continue to execute. Therefore when the information you wish to reference from another file is essential to the correct running of a page, use require.

67)Is PHP a case sensitive programming language?

PHP is a partially case sensitive programming language. We can use function names, class names in case insensitive manner.

68)What is mean by LAMP?

LAMP means combination of Linux, Apache, MySQL and PHP.

69)How do you get the user’s ip address in PHP?

Using the server variable: $_SERVER[‘REMOTE_ADDR’]

70)How do you make one way encryption for your passwords in PHP?

Using md5 function or sha1 function

71)What is meant by PEAR in php?

Answer1: PEAR is the next revolution in PHP. This repository is bringing higher level programming to PHP. PEAR is a framework and distribution system for reusable PHP components. It eases installation by bringing an automated wizard, and packing the strength and experience of PHP users into a nicely organised OOP library. PEAR also provides a command-line interface that can be used to automatically install “packages”

PEAR is short for “PHP Extension and Application Repository” and is pronounced just like the fruit. The purpose of PEAR is to provide:
A structured library of open-sourced code for PHP users
A system for code distribution and package maintenance
A standard style for code written in PHP
The PHP Foundation Classes (PFC),
The PHP Extension Community Library (PECL),
A web site, mailing lists and download mirrors to support the PHP/PEAR community
PEAR is a community-driven project with the PEAR Group as the governing body. The project has been founded by Stig S. Bakken in 1999 and quite a lot of people have joined the project since then.

72)How can we repair a MySQL table?

The syntex for repairing a mysql table is:

REPAIR TABLE tablename

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.

73)What is the difference between echo and print statement?

Echo() can take multiple expressions,Print cannot take multiple expressions.

Print return true or false based on success or failure whereas echo just does what its told without letting you know whether or not it worked properly.

74)What are the features and advantages of OBJECT ORIENTED PROGRAMMING?

One of the main advantages of OO programming is its ease of modification; objects can easily be modified and added to a system there by reducing maintenance costs. OO programming is also considered to be better at modeling the real world than is procedural programming. It allows for more complicated and flexible interactions. OO systems are also easier for non-technical personnel to understand and easier for them to participate in the maintenance and enhancement of a system because it appeals to natural human cognition patterns.

For some systems, an OO approach can speed development time since many objects are standard across systems and can be reused. Components that manage dates, shipping, shopping carts, etc. can be purchased and easily modified for a specific system.

75)What is the value of $b in the following code?
$a=”5 USD”;
echo $b;


76)What are the differences between Get and post methods in form submitting, give the case where we can use get and we can use post methods?

In the get method the data made available to the action page ( where data is received ) by the URL so data can be seen in the address bar. Not advisable if you are sending login info like password etc.

In the post method the data will be available as data blocks and not as query string.

77)What is GPC?

G – Get
P – Post
C – Cookies

78)What are super global arrays?

All variables that come into PHP arrive inside one of several special arrays known collectively as the superglobals. They’re called superglobal because they are available everywhere in your script, even inside classes and functions.
5:Give some example for super global arrays?

79)What’s the difference between COPY OF A FILE & MOVE_UPLOAD_FILE in file uploading?

MOVE_UPLOAD_FILE :   This function checks to ensure that the file designated by filename is a valid upload file (meaning that it was uploaded via PHP’s HTTP POST upload mechanism). If the file is valid, it will be moved to the filename given by destination.
If filename is not a valid upload file, then no action will occur, and move_uploaded_file() will return FALSE.
Copy :Makes a copy of a file. Returns TRUE if the copy succeeded, FALSE otherwise.

80)When I do the following, the output is printed in the wrong order:

function myfunc($argument) {
echo $argument + 10;
$variable = 10;
echo “myfunc($variable) = ” . myfunc($variable);

What’s going on?
To be able to use the results of your function in an expression (such as concatenating it with other strings in the example above), you need to return the
value, not echo it.

81)What are the Formatting and Printing Strings available in PHP?

Function                     Description
printf()    :                 Displays a formatted string
sprintf()   :                 Saves a formatted string in a variable
fprintf()   :                 Prints a formatted string to a file
number_format()  :   Formats numbers as strings

82)Explain the types of string comparision function in PHP.

Function              Descriptions
strcmp()             :Compares two strings (case sensitive)
strcasecmp()      :Compares two strings (not case sensitive)
strnatcmp(str1, str2) :Compares two strings in ASCII order, but
any numbers are compared numerically
strnatcasecmp(str1, str2):Compares two strings in ASCII order,
case insensitive, numbers as numbers
strncasecomp()  : Compares two strings (not case sensitive)
and allows you to specify how many characters
to compare
strspn()             : Compares a string against characters represented
by a mask
strcspn()           : Compares a string that contains characters not in
the mask

83)Explain soundex() and metaphone().

The soundex() function calculates the soundex key of a string. A soundex key is a four character long alphanumeric string that represent English pronunciation of a word. he soundex() function can be used for spelling applications.
$str = “hello”;
echo soundex($str);
The metaphone() function calculates the metaphone key of a string. A metaphone key represents how a string sounds if said by an English speaking person. The metaphone() function can be used for spelling applications.
echo metaphone(“world”);

84)What do you mean range()?

Starting from a low value and going to a high value, the range() function creates an array of consecutive integer or character values. It takes up to three arguments: a starting value, an ending value, and an increment value. If only two arguments are given, the increment value defaults to 1.
Example :
echo range(1,10); // Returns 1,2,3,4,5,6,7,8,9,10

85)How to read and display a HTML source from the website url?

$fh=fopen(“$filename”, “r”);
while( !feof($fh) ){
$contents=htmlspecialchars(fgets($fh, 1024));
print ”

86)What is properties of class?

Class member variables are called “properties”. We may also see them referred to using other terms such as “attributes” or “fields”, but for the purposes of this reference we will use “properties”. They are defined by using one of the keywords public, protected, or private, followed by a normal variable declaration. This declaration may include an initialization, but this initialization must be a constant value that is, it must be able to be evaluated at compile time and must not depend on run-time information in order to be evaluated.

87)How to use HTTP Headers inside PHP? Write the statement through which it can be added?

HTTP headers can be used in PHP by redirection which is written as:
The headers can be added to HTTP response in PHP using the header(). The response headers are sent before any actual response being sent. The HTTP headers have to be sent before taking the output of any data. The statement above gets included at the top of the script.

88)Why we used PHP?

Because of several main reason we have to use PHP. These are:
1.PHP runs on many different platforms like that Unix,Linux and Windows etc.
2.It codes and software are free and easy to download.
3.It is secure because user can only aware about output doesn’t know how that comes.
4.It is fast,flexible and reliable.
5.It supports many servers like: Apache,IIS etc.

89)Arrays  in PHP?

Create array in PHP to solved out the problem of writing same variable name many time.In this we create a array of variable name and enter the similar variables in terms of element.Each element in array has a unique key.Using that key we can easily access the wanted element.Arrays are essential for storing, managing and operating on sets of variables effectively. Array are of three types:
1.Numeric array
2.Associative array
3.Multidimensional array
Numeric array is used to create an array with a unique key.Associative array is used to create an array where each unique key is associated with their value.Multidimensional array is used when we declare multiple arrays in an array.

90)What is foreach loop in  php?

foreach:Uses, When When we want execute a block of code for each element in an array.
foreach (array as value)
code will be executed;
$arr=array(“one”, “two”, “three”);
foreach ($arr as $value)
echo “Value: ” . $value . ”

91)How we used $_get and $_post variable in PHP?

We know that when we use $_GET variable all data_values are display on our URL.So,using this we don’t have to send secret data (Like:password, account code).But using we can bookmarked the importpage.
We use $_POST variable when we want to send data_values without display on URL.And their is no limit to send particular amount of character.
Using this we can not bookmarked the page.

92)Why we use $_REQUEST variable?

We use $_REQUEST variable in PHP to collect the data_values from $_GET,$_POST and $_COOKIE variable.
R4R Welcomes You .

You are years old!

93)How we handle errors in PHP?Explain it?

In PHP we can handle errors easily.Because when error comes it gives error line with their respective line and send error message to the web browser.
When we creating any web application and scripts. We should handle errors wisely.Because when this not handle properly it can make bg hole in security.
In PHP we handle errors by using these methods:
1.Simple “die()” statements
2.Custom errors and error triggers
3.Error reporting

94)How we use Custom errors and error triggers error handling method in PHP?

In Custom errors and error triggers,we handle errors by
using self made functions.
1.Custom errors : By using this can handle the multiple
errors that gives multiple message.
In this syntax if we want that our error handle, handle
only one error than we write only one argument otherwise
for handle multiple errors we can write multiple arguments.

//function made to handle errorfunction
custom_Error($errorno, $errorstr)
echo \”Error: [$errorno] $errorstr\”;  }
//set error handler like that
//trigger to that error

2.error trigger : In PHP we use error trigger to handle
those kind of error when user enter some input data.If
data has an error than handle by error trigger function.

$i=0;if ($i<=1)
trigger_error(\”I should be greater than 1 \”);
In this trigger_error function generate error when i is
less than or greater than 1.

95)What do you understand about Exception Handling in PHP?

In PHP 5 we introduce a Exception handle to handle run time exception.It is used to change the normal flow of the code execution if a specified error condition occurs.
An exception can be thrown, and caught(“catched”) within PHP. Write code in try block,Each try must have at least one catch block. Multiple catch blocks can be used to catch different classes of exceptions.
Some error handler methods given below:
1.Basic use of Exceptions
2.Creating a custom exception handler
3.Multiple exceptions
4.Re-throwing an exception
5.Setting a top level exception handler

96)What is the difference b/n ‘action’ and ‘target’ in form tag?

Action attribute specifies where to send the form-data when
a form is submitted.
The target attribute specifies where to open the action URL.
_blank – open in new window
_self- Open in the same frame as it was clicked
_parent- Open in the parent frameset
_top- Open in the full body of the window
Framename- Open in a named frame

97)How we use ceil() and floor() function in PHP?

ceil() is use to find nearest maximum values of passing value.
echo $ans_var;
floor() is use to find nearest minimum values of passing value.
echo $ans_var;

98)What is the answer of following code

echo 1< 2 and echo 1 >2 ?

Output of the given code are given below:
echo 1<2
output: 1
echo 1>2
output: no output

99)What is the difference b/w isset and empty? 
The main difference b/w isset and empty are given below:
isset: This variable is used to handle functions and checked a variable is set even through it is empty.
empty: This variable is used to handle functions and checked either variable has a value or it is an empty string,zero0 or not set at all.

100)What do you understand about PHP accelerator ? 

Basically PHP accelerator is used to boost up the performance of PHP programing language.We use PHP accelerator to reduce the server load and also use to enhance the performance of PHP code near about 2-10 times.In one word we can say that PHP accelertator is code optimization technique.


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