Welcome !!!. In this section we are providing you some frequently asked PHP Interview Questions which will help you to win interview session easily. Candidates must read this section,Then by heart the questions and answers. Also, review sample answers and advice on how to answer
these typical interview questions. PHP is an important part of the web
world, and every web developer should have the basic knowledge in
PHP.Common PHP interview questions, which should help you become a
best PHP codder. We hope you find these questions useful. If you are an
interviewer, Take the time to read the common interview questions you will most likely be asked.
27. How to strip whitespace (or other characters) from the
beginning and end of a string ?
1.
What is
PHP?
PHP is a
server side scripting language commonly used for web applications. PHP has many
frameworks and cms for creating websites.Even a non technical person can cretae
sites using its CMS.WordPress,osCommerce are the famus CMS of php.It is also an
object oriented programming language like java,C-sharp etc.It is very eazy for
learning
2.
What is
the use of "echo" in php?
It is used
to print a data in the webpage, Example: <?php echo 'Car insurance'; ?> ,
The following code print the text in the webpage
3.
How to
include a file to a php page?
We can
include a file using "include() " or "require()" function
with file path as its parameter.
4.
What's the
difference between include and require?
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.
5.
require_once(),
require(), include().What is difference between them?
require()
includes and evaluates a specific file, while require_once() does that only if
it has not been included before (on the same page). So, require_once() is recommended
to use when you want to include a file where you have a lot of functions for
example. This way you make sure you don't include the file more times and you
will not get the "function re-declared" error.
6.
Differences
between GET and POST methods ?
We can
send 1024 bytes using GET method but POST method can transfer large amount of
data and POST is the secure method than GET method .
7.
How to
declare an array in php?
Eg : var
$arr = array('apple', 'grape', 'lemon');
8.
What is
the use of 'print' in php?
This is
not actually a real function, It is a language construct. So you can use with
out parentheses with its argument list.
Example print('PHP Interview questions');
print 'Job Interview ');
Example print('PHP Interview questions');
print 'Job Interview ');
9.
What is
use of in_array() function in php ?
in_array used to checks if a value exists in an array
10. What is use of count() function in php ?
count() is used to count all elements in an array, or something in
an object
11. What’s the difference between include and require?
It’s 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.
12. What is the difference between Session and Cookie?
The main
difference between sessions and cookies is that sessions are stored on the
server, and cookies are stored on the user’s computers in the text file format.
Cookies can not hold multiple variables,But Session can hold multiple
variables.We can set expiry for a cookie,The session only remains active as
long as the browser is open.Users do not have access to the data you stored in
Session,Since it is stored in the server.Session is mainly used for
login/logout purpose while cookies using for user activity tracking
13. How to set cookies in PHP?
Setcookie("sample",
"ram", time()+3600);
14. How to Retrieve a Cookie Value?
eg : echo
$_COOKIE["user"];
15. How to create a session? How to set a value in session ? How
to Remove data from a session?
Create
session : session_start();
Set value into session : $_SESSION['USER_ID']=1;
Remove data from a session : unset($_SESSION['USER_ID'];
Set value into session : $_SESSION['USER_ID']=1;
Remove data from a session : unset($_SESSION['USER_ID'];
16. what types of loops exist in php?
for,while,do
while and foreach (NB: You should learn its usage)
17. How to create a mysql connection?
mysql_connect(servername,username,password);
18. How to select a database?
mysql_select_db($db_name);
19. How to execute an sql query? How to fetch its result ?
$my_qry =
mysql_query("SELECT * FROM `users` WHERE `u_id`='1'; ");
$result = mysql_fetch_array($my_qry);
echo $result['First_name'];
$result = mysql_fetch_array($my_qry);
echo $result['First_name'];
20. Write a program using while loop
$my_qry =
mysql_query("SELECT * FROM `users` WHERE `u_id`='1'; ");
while($result = mysql_fetch_array($my_qry))
{
echo $result['First_name'.]."<br/>";
}
while($result = mysql_fetch_array($my_qry))
{
echo $result['First_name'.]."<br/>";
}
21. How we can retrieve the data in the result set of MySQL
using PHP?
o
1. mysql_fetch_row
o
2. mysql_fetch_array
o
3. mysql_fetch_object
o
4. mysql_fetch_assoc
22. What is the use of explode() function ?
Syntax :
array explode ( string $delimiter , string $string [, int $limit ] );
This function breaks a string into an array. Each of the array elements is a substring of string formed by splitting it on boundaries formed by the string delimiter.
This function breaks a string into an array. Each of the array elements is a substring of string formed by splitting it on boundaries formed by the string delimiter.
23. What is the difference between explode() and split()
functions?
Split
function splits string into array by regular expression. Explode splits a
string into array by string.
24. What is the use of mysql_real_escape_string() function?
It is used
to escapes special characters in a string for use in an SQL statement
25. Write down the code for save an uploaded file in php.
if ($_FILES["file"]["error"]
== 0)
{
move_uploaded_file($_FILES["file"]["tmp_name"],
"upload/" . $_FILES["file"]["name"]);
echo "Stored in: " . "upload/" . $_FILES["file"]["name"];
}
{
move_uploaded_file($_FILES["file"]["tmp_name"],
"upload/" . $_FILES["file"]["name"]);
echo "Stored in: " . "upload/" . $_FILES["file"]["name"];
}
26. How to create a text file in php?
$filename
= "/home/user/guest/newfile.txt";
$file = fopen( $filename, "w" );
if( $file == false )
{
echo ( "Error in opening new file" ); exit();
}
fwrite( $file, "This is a simple test\n" );
fclose( $file );
$file = fopen( $filename, "w" );
if( $file == false )
{
echo ( "Error in opening new file" ); exit();
}
fwrite( $file, "This is a simple test\n" );
fclose( $file );
The trim()
function removes whitespaces or other predefined characters from both sides of
a string.
28. What is the use of header() function in php ?
The
header() function sends a raw HTTP header to a client browser.Remember that
this function must be called before sending the actual out put.For example, You
do not print any HTML element before using this function.
29. How to redirect a page in php?
The
following code can be used for it, header("Location:index.php");
30. How stop the execution of a php scrip ?
exit() function is used to stop the execution of a page
31. How to set a page as a home page in a php based site ?
index.php is the default name of the home page in php based sites
32. How to find the length of a string?
strlen() function used to find the length of a string
33. what is the use of rand() in php?
It is used
to generate random numbers.If called without the arguments it returns a
pseudo-random integer between 0 and getrandmax(). If you want a random number
between 6 and 12 (inclusive), for example, use rand(6, 12).This function does
not generate cryptographically safe values, and should not be used for
cryptographic uses. If you want a cryptographically secure value, consider
using openssl_random_pseudo_bytes() instead.
34. what is the use of isset() in php?
This
function is used to determine if a variable is set and is not NULL
35. What is the difference between mysql_fetch_array() and
mysql_fetch_assoc() ?
mysql_fetch_assoc function Fetch a result row as an associative array, While mysql_fetch_array()
fetches an associative array, a numeric array, or both
36. What is mean by an associative array?
Associative
arrays are arrays that use string keys is called associative arrays.
37. What is the importance of "method" attribute in a
html form?
"method"
attribute determines how to send the form-data into the server.There are two
methods, get and post. The default method is get.This sends the form
information by appending it on the URL.Information sent from a form with the
POST method is invisible to others and has no limits on the amount of
information to send.
38. What is the importance of "action" attribute in a
html form?
The action
attribute determines where to send the form-data in the form submission.
39. What is the use of "enctype" attribute in a html
form?
The
enctype attribute determines how the form-data should be encoded when
submitting it to the server. We need to set enctype as "multipart/form-data"
when we are using a form for uploading files
40. How to create an array of a group of items inside an HTML
form ?
We can
create input fields with same name for "name" attribute with squire
bracket at the end of the name of the name attribute, It passes data as an
array to PHP.
For instance :
For instance :
<input
name="MyArray[]" />
<input name="MyArray[]" /> <input name="MyArray[]"
/> <input name="MyArray[]"
/>
41. Define Object-Oriented Methodology
Object
orientation is a software/Web development methodology that is based on the
modeling a real world system.An object is the core concept involved in the
object orientation. An object is the copy of the real world enity.An object
oriented model is a collection of objects and its inter-relationships
42. How do you define a constant?
Using
define() directive, like define ("MYCONSTANT",150)
43. How send email using php?
To send
email using PHP, you use the mail() function.This mail() function accepts 5
parameters as follows (the last 2 are optional). You need webserver, you can't
send email from localhost. eg : mail($to,$subject,$message,$headers);
44. How to find current date and time?
The date()
function provides you with a means of retrieving the current date and time,
applying the format integer parameters indicated in your script to the
timestamp provided or the current local time if no timestamp is given. In
simplified terms, passing a time parameter is optional - if you don't, the
current timestamp will be used.
45. Difference between mysql_connect and mysql_pconnect?
There is a
good page in the php manual on the subject, in short mysql_pconnect() makes a
persistent connection to the database which means a SQL link that do not close
when the execution of your script ends. mysql_connect()provides only for the
databasenewconnection while using mysql_pconnect , the function would first try
to find a (persistent) link that's already open with the same host, username
and password. If one is found, an identifier for it will be returned instead of
opening a new connection... the connection to the SQL server will not be closed
when the execution of the script ends. Instead, the link will remain open for
future use.
46. What is the use of "ksort" in php?
It is used
for sort an array by key in reverse order.
47. What is the difference between $var and $$var?
They are
both variables. But $var is a variable with a fixed name. $$var is a variable
who's name is stored in $var. For example, if $var contains
"message", $$var is the same as $message.
48. What are the encryption techniques in PHP
MD5 PHP implements the MD5 hash algorithm using the md5 function,
eg : $encrypted_text = md5 ($msg);
eg : $encrypted_text = md5 ($msg);
mcrypt_encrypt :- string mcrypt_encrypt ( string $cipher , string $key ,
string $data , string $mode [, string $iv ] );
Encrypts plaintext with given parameters
Encrypts plaintext with given parameters
49. What is the use 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.
50. How to delete a file from the system
Unlink()
deletes the given file from the file system.
51. How to get the value of current session id?
session_id()
function returns the session id for the current session.
52. What are the differences between mysql_fetch_array(),
mysql_fetch_object(), mysql_fetch_row()?
o
Mysql_fetch_array Fetch a result row
as an associative array, a numeric array, or both.
o
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
o
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.
53. What are the different types of errors in PHP ?
Here are
three basic types of runtime errors in PHP:
o
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.
o
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.
o
3. Fatal errors: These are critical
errors - for example, instantiating an object of a non-existent 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.
54. what is sql injection ?
SQL
injection is a malicious code injection technique.It exploiting SQL
vulnerabilities in Web applications
55. What is x+ mode in fopen() used for?
Read/Write.
Creates a new file. Returns FALSE and an error if file already exists
56. How to find the position of the first occurrence of a
substring in a string
strpos() is used to find the position of the first occurrence of a
substring in a string
57. What is PEAR?
PEAR is a
framework and distribution system for reusable PHP components.The project seeks
to provide a structured library of code, maintain a system for distributing
code and for managing code packages, and promote a standard coding style.PEAR
is broken into three classes: PEAR Core Components, PEAR Packages, and PECL
Packages. The Core Components include the base classes of PEAR and PEAR_Error,
along with database, HTTP, logging, and e-mailing functions. The PEAR Packages
include functionality providing for authentication, networking, and file system
features, as well as tools for working with XML and HTML templates.
58. Distinguish between urlencode and urldecode?
This
method is best when encode a string to used in a query part of a url. it
returns a string in which all non-alphanumeric characters except -_. have
replece with a percentege(%) sign . the urldecode->Decodes url to encode
string as any %and other symbole are decode by the use of the urldecode()
function.
59. What are the different errors in PHP?
In PHP,
there are three types of runtime errors, they are:
Warnings:
These are important errors. Example: When we try to include () file which is not available. These errors are showed to the user by default but they will not result in ending the script.
Notices:
These errors are non-critical and trivial errors that come across while executing the script in PHP. Example: trying to gain access the variable which is not defined. These errors are not showed to the users by default even if the default behavior is changed.
Fatal errors:
These are critical errors. Example: instantiating an object of a class which does not exist or a non-existent function is called. These errors results in termination of the script immediately and default behavior of PHP is shown to them when they take place. Twelve different error types are used to represent these variations internally.
These are important errors. Example: When we try to include () file which is not available. These errors are showed to the user by default but they will not result in ending the script.
Notices:
These errors are non-critical and trivial errors that come across while executing the script in PHP. Example: trying to gain access the variable which is not defined. These errors are not showed to the users by default even if the default behavior is changed.
Fatal errors:
These are critical errors. Example: instantiating an object of a class which does not exist or a non-existent function is called. These errors results in termination of the script immediately and default behavior of PHP is shown to them when they take place. Twelve different error types are used to represent these variations internally.
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