Interview Questions PHP

PHP Interview Questions And Answers for Freshers 2020

Hello Guys !! In this section, we are providing you some frequently asked PHP Interview Questions which will help you to win the 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.

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. Some Interview question with answers are listed below:

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 nontechnical person can create sites using its CMS. WordPress, osCommerce are the famous CMS of PHP. It is also an object-oriented programming language like java, C-sharp, etc. It is very easy for learning

Whats the full form of PHP ?

Initially, it was Personal Home Page, but now its PHP: Hypertext Preprocessor. It is funny to think that Letter P in PHP stands for PHP itself. H stands for Hypertext and P stands for Preprocessor.

Who is known as father of PHP?

Rasmus Lerdorf

What is the use of echo in php?

It is used to print a data in the web page

echo "PHP Interview Questions";

The above code will print the text in the web page.

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.

What’s the difference between include and require?


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.

Differences between GET and POST methods ?

We can send 1024 bytes using the GET method but the POST method can transfer large amounts of data and POST is the secure method than GET method.

How to declare an array in php?

We can declare an array in two ways

//An array can be created using the array() language construct
$colors_arr = array("red", "black", "yellow", "white");
// using key => value pairs
$countries_arr = array(
			"IN" => "India", 
			"US" => "United States", 
			"UK" =>"United Kingdom"
// as of PHP 5.4
$languages_arr = ["PHP", "JavaScript", "Python", "Java"];

What is the use of  print in php?

This is not actually a real function, It is a language construct. So you can use without parentheses with its argument list.


print("PHP Interview questions");
print "Job Interview";

What is use of in_array() function in php ?

in_array() used to checks if a value exists in an array

What is use of count() function in php ?

count() is used to count all elements in an array, or something in an object

What’s the difference between include and require?


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. The session is mainly used for login/logout purpose while cookies using for user activity tracking

How to set cookies in PHP?

// set cookie
setcookie("sample", "ram", time()+3600);

How to Retrieve a Cookie Value?

We can retrieve cookie value as follows

echo $_COOKIE["user"];

How to create a session? How to set a value in session? How to remove data from a session?

//Creat session
//Set value into session
//Remove data from a session

what types of loops exist in PHP?

for, while, do-while and foreach (You should learn its usage)

How to create a MySQL connection in PHP?

$conn = mysqli_connect("hostname","username","password");
// Object oriented style
$mysqli = new mysqli("hostname","username","password", "dbname");

How to select a database?

mysqli_select_db($db_conn, "database_name");
// object oriented style

How to execute an sql query? How to fetch its result ?

$my_query = mysqli_query("SELECT * FROM `users` WHERE `u_id`='1'; ");
$result = mysqli_fetch_array($my_query);
echo $result['First_name'];

Write a program using while loop

while($result = mysqli_fetch_array($my_qry))
echo $result['First_name']."<br/>";

How we can retrieve the data in the result set of MySQL using PHP?

1. mysqli_fetch_row

2. mysqli_fetch_array

3. mysqli_fetch_object

4. mysqli_fetch_assoc

What is the use of explode() function ?

Syntax : array explode ( string $delimiter , string $string [, int $limit ] );

// explode example
$str = "This is an example of PHP explode function";
$arr = explode(" ", $str);
echo "<pre>";
// output 
    [0] => This
    [1] => is
    [2] => an
    [3] => example
    [4] => of
    [5] => PHP
    [6] => explode
    [7] => function

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.

What is the difference between explode() and split() functions?

Split() function splits the string into array by regular expression. explode() splits a string into array by string.

What is the use of mysqli_real_escape_string() function?

It is used to escapes special characters in a string for use in an SQL statement

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"];

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");

How to strip whitespace (or other characters) from the beginning and end of a string?

The trim() function removes whitespaces or other predefined characters from both sides of a string.

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 output. For example, You do not print any HTML element before using this function.

How to redirect a page in php?

The following code can be used for it.


How stop the execution of a php scrip ?

exit() function is used to stop the execution of a page

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

How to find the length of a string?

strlen() function used to find the length of a string

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).

$random_num = 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.

what is the use of isset() in PHP?

This function is used to determine if a variable is set and is not NULL

What is the difference between mysqli_fetch_array() and mysqli_fetch_assoc() ?

mysqli_fetch_assoc() function Fetch a result row as an associative array, while mysqli_fetch_array() fetches an associative array, a numeric array, or both

What is mean by an associative array?

Associative arrays are arrays that use string keys is called associative arrays.

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.

What is the importance of “action” attribute in a html form?

The action attribute determines where to send the form-data in the form of submission.

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

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 :

<input name="MyArray[]" />  
<input name="MyArray[]" />  
<input name="MyArray[]" />  
<input name="MyArray[]" />  

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 a copy of the real-world entity. An object-oriented model is a collection of objects and its inter-relationships

How do you define a constant?

Using define() directive, like

 define ("MYCONSTANT",150);

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 a web server, you can’t send email from localhost. eg :


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.

Difference between mysqli_connect and mysqli_pconnect?

There is a good page in the PHP manual on the subject, in short mysqli_pconnect() makes a persistent connection to the database which means a SQL link that do not close when the execution of your script ends. mysqli_connect() provides only for the database new connection while using mysqli_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.

What is the use of “ksort” in php?

It is used for sort an array by key in reverse order.

What is the difference between $var and $$var?

They are both variables. But $var is a variable with a fixed name. $$var is a variable whose name is stored in $var. For example, if $var contains “message”, $$var is the same as $message.

What are the encryption techniques in PHP?

MD5 PHP implements the MD5 hash algorithm using the md5 function, e.g.

$encrypted_text = md5 ($msg);
string mcrypt_encrypt( string $cipher, string $key, 
string $data, string $mode [, string $iv ] );

Encrypts plaintext with given parameters

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.

How to delete a file from the system?

unlink() deletes the given file from the file system.

How to get the value of current session id?

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

What are the differences between mysqli_fetch_array(), mysqli_fetch_object(), mysqli_fetch_row()?

mysqli_fetch_array() fetch a result row as an associative array, a numeric array, or both.

mysqli_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

mysqli_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.

What are the different types of errors in PHP ?

Here are three basic types of runtime errors in PHP:


2. Warnings: These are more serious errors – for example, attempting to include() a file that 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 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.

what is sql injection ?

SQL injection is a malicious code injection technique. It exploiting SQL vulnerabilities in Web applications

What is x+ mode in fopen() used for?

Read/Write. Creates a new file. Returns FALSE and an error if file already exists

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

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.

Distinguish between urlencode and urldecode?

urlencode() method is best when encode a string to use in a query part of a URL. It returns a string in which all non-alphanumeric characters except -_. have replaced with a percentage(%) sign. The urldecode() decodes URL to encode the string as any %and other symbols are decode by the use of the urldecode() function.

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