Top 55 PHP Interview Questions and Answers

One of the most widely used programming languages for web development is PHP. PHP is used by 79 percent of websites, according to statistics, because of its simplicity, logic, and clarity. To make your interview process go more smoothly, we’ve compiled a list of frequently asked PHP developer Interview questions based on expert opinions. This is a set of PHP and its framework interview questions. This article combines the queries for PHP interview questions and answers for freshers and PHP interview questions for the experienced and hence it’s appropriate for both beginners and professional PHP developers.

Preparing for these questions will boost your confidence and allow you to settle in the interview.

TOP 55 PHP INTERVIEW QUESTIONS AND ANSWERS

1. What is PHP?

PHP is an acronym for Hypertext Preprocessor. It is a commonly used open-source server-side scripting language for web development. Many databases are supported, including MySQL, Oracle, Sybase, Solid, PostgreSQL, and Generic ODBC.

2. PHP is similar to which programming language?

PHP syntax is similar to Perl and C Programming.

3. Tell me about PEAR in PHP?

PEAR is a framework and repository for PHP components that can be reused. PEAR is an acronym for PHP Extension and Application Repository. It’s full of PHP code snippets and libraries of all kinds.

4. What is the currently used PHP version?

PHP version 7.1 or 7.2 is the preferred version now.

5. How to execute the PHP script from the command line?

Simply use the PHP command-line interface (CLI) and enter the following as the file name of the script to run:

PHP script.php

6. How will you display the output directly to the browser?

We must use the special tags?= and?> to display the output directly to the browser.

7. Does PHP support Multiple Inheritance?

PHP only supports single inheritance, which implies that a class can be extended by using the keyword ‘extended’ from only one other class.

8. How to compare objects in PHP?

To see if two objects are instanced from the same class and have the same characteristics and values, we use the operator ‘==’. The identity operator ‘===’ can be used to see if two objects refer to the same instance of the same class.

9. How do we use PHP to find the number of rows in a result set?

$result = mysql_query($sql, $db_link);

$num_rows = mysql_num_rows($result);

echo “$num_rows rows found”;

10. Will PHP and HTML interact?

PHP scripts can generate HTML and pass data between the two. In this way, they both interact with each other.

11. Tell the meaning of the final class and final method?

In PHP5, the term ‘final’ was used for the first time. The term “final class” refers to a class that cannot be extended and the final method cannot be overridden.

12. In PHP, which feature counts the total number of rows returned by any query?

To count the total number of rows returned by the query, use the mysqli_num_rows() function.

$mysqli = mysqli_connect(“hostname”,”username”,”password”,”DBname”);

$result=mysqli_query($mysqli,”select * from employees”);

$count=mysqli_num_rows($result);

13. How can we pass values through a form or URL in PHP?

We need to encode and decode the values using htmlspecialchars() and urlencode() if we would like to pass values through a form or an URL.

14. How do we use the date feature to get the second of the current time?

<?php

$second = date(“s”);

?>

15. Mention the important features of PHP7?

The important features of the PHP7 version are updated below,

• Scalar type declarations

• Return type declarations

• Null coalescing operator (??)

• Constant arrays using define()

• Anonymous classes

• Closure::call method

• Group use declaration

• Generator return expressions

• Generator delegation

• Spaceship operator

16. List the popularly known frameworks in PHP?

The below are the commonly used Frameworks in PHP,

• CakePHP

• CodeIgniter

• Yii 2

• Symfony

• Zend Framework

17. Tell us about Joomla and Magento?

JOOMLA: Open Source Matters, Inc. developed Joomla, a free and open-source content management system (CMS) for distributing web content. It’s built on a model-view-controller web application framework that can work without a CMS.

MAGENTO: Magento is a valuable open-source E-commerce programming created by Varien Inc. for online businesses. It has a flexible measured design and is versatile, with a variety of control options that customers will find useful. Magento is an e-commerce platform that provides businesses with comprehensive E-business options and a large support network.

18. Tell me how many data types are there in PHP?

Data types in PHP are used to store various kinds of data or values. There are eight primitive data types, which are further divided into three categories:

• Scalar types

• Compound types

• Special types

19. Tell us about PHP parameterized functions?

Functions with parameters are known as PHP parameterized functions. Within a function, you can pass any number of parameters. Within your function, these parameters are used as variables. After the function name, they are defined within the parentheses. The function’s output is determined by the dynamic values passed in as parameters.

20. How to declare a function that receives one parameter name hello?

In the below code, if hello is true, then the function should print hello, but if the function doesn’t receive hello then the hello is false and the function must print bye.

<?php

function showMessage($hello=false)

{

echo ($hello)?’hello’:’bye’;

}

?>

21. Is it possible to give a PHP script an infinite execution time?

The set_time_limit(0) directive at the start of a script sets the execution time to infinite to avoid the PHP error ‘maximum execution time exceeded. This can also be specified in the php.ini configuration file.

22. What’s the difference between require() and require_once(), exactly?

More or less both are similar. The only difference between require() and require_once() is that require_once() checks if the PHP script is already included before executing it.

23. What do you mean by the PHP error ‘Parse error in PHP – unexpected T_variable at line x’?

This is a PHP syntax error indicating that a mistake on line x prevents the program from parsing and running.

24. What is the function file_get_contents() useful for?

file_get_contents() always reads a file and stores it in a string variable.

25. How to connect a MySQL database from a PHP script?

To connect a MySQL database, we must use mysqli_connect() function as follows:

<!–?php $database = mysqli_connect(“HOST”, “USER_NAME”, “PASSWORD”); mysqli_select_db($database,”DATABASE_NAME”); ?–>

26. Why is mysql_pconnect() function used?

mysql_pconnect() maintains a persistent database connection, which means the connection does not close when the PHP script terminates.

In PHP 7.0 and higher, this function is not supported.

27. Mention the main difference between mysqli_fetch_object() and mysqli_fetch_array()?

The mysqli_fetch_object() function collects the very first single matching record where mysqli_fetch_array() usually collects all records that are matching from the table in an array.

28. How to export the data into the excel file?

The most common and widely used method is to get data into an Excel-compatible format. It is possible, for example, to create a .csv file, select comma as a field separator, and then open the file in Excel.

29. Tell me about the PHP variable-length argument function?

PHP has a function that accepts variable-length arguments. It means that you should pass zero, one, or n arguments to the function. To do this, place three ellipses (dots) before the argument name. Since PHP 5.6, the three-dot principle has been introduced for variable-length arguments.

30. Explain the types of the array in PHP?

There are 3 types of array used in PHP:

INDEXED ARRAY: An array with a numeric key is called an indexed array.

ASSOCIATIVE ARRAY: An associative array is one in which each key has a unique value.

MULTI-DIMENSIONAL ARRAY: An array that contains one or more arrays within it is called a multidimensional array.

31.If you get a form in the mail to subscribe to a newsletter. This type only has one field, an email input text field. What method will you use to check if the field is empty? In this case, print the message “The email cannot be null.”

<?php

if(empty($_POST[’email’])){

echo “The email cannot be empty”;

}

?>

32. What are the purposes of the functions explode() and implode()?

The explode() function is used to divide a string into an array, and the implode() function is used to merge the array elements into a string.

$text = “I like php programming”;

print_r (explode(” “,$text));

$strarr = array(‘sky’,’star’,’sun’);

echo implode(” “,$strarr);

33. What do you know about the setcookie() function in PHP?

To set a cookie with an HTTP response, use the PHP setcookie() function. The $_COOKIE superglobal variable can be used to access the cookie once it has been set.

34. Explain Session in PHP?

The PHP Engine generates a logical object called a session to keep data consistent across HTTP requests.

Sessions are used to store temporary data so that different PHP pages will give the same user a fully functional transaction.

Simply put, it keeps track of a user’s information (browser).

35. Tell the method to register a value into a session?

We can register a value in a session by,

<?php

Session_register($ur_session_var);

?>

36. Tell me the difference between a session and a cookie?

The primary difference between a session and a cookie is that cookies are stored in text file format on the user’s computer, while sessions are stored on the server.

Cookies, on the other hand, cannot hold different variables; however, Session can.

A cookie can be set to expire at any time, while a session is only active as long as the browser is open.

37. Write down the syntax to open a file in PHP?

The PHP fopen() function opens a file or a URL and returns the resource. $filename and $mode are the two arguments it accepts.

Below is the syntax for opening a file in PHP,

resource fopen ( string $filename , string $mode [, bool $use_include_path = false [, resource $context ]] )

38. How will you send email in PHP?

Through the mail() function an email could be sent in PHP.

bool mail($to,$subject,$message,$header); is the syntax of the mail() function to send mails via PHP.

39. Explain the different types of errors in PHP?

In PHP, there are three kinds of errors.

NOTICES: This is a list of non-critical errors. Users are not informed of these mistakes.

WARNINGS: These are more serious mistakes, but they do not terminate the screenplay. These errors are presented to the user by default.

FATAL ERRORS: These are the most serious mistakes that can be made. These errors may occur as a result of the script being terminated too soon.

40. What will be the output of the following code?

$i = 016;

echo $i / 2;

The output and answer is 7. Since the leading zero in PHP indicates an octal number, the number evaluates to decimal 14 rather than decimal 16.

41. How can we get the browser properties using PHP?

<?php

echo $_SERVER[‘HTTP_USER_AGENT’].”\n\n”;

$browser=get_browser(null,true);

print_r($browser);

?>

42. Tell me about htaccess in PHP?

The.htaccess file is an Apache server configuration file. Directives in Apache configuration files such as .htaccess and httpd.conf can be used to alter configuration settings.

43. Tell me the importance of Parser in PHP?

From the opening to the closing tag, the PHP parser parses the PHP-developed website. Tags indicate where PHP code is started and where it ends. In other words, the scope of PHP scripting syntax is determined by the opening and closing tags.

<?php syntax of opening tag in PHP

?> syntax of closing tag in PHP

44. How to build a database using PHP and MYSQL?

The following are the steps to build a MySQL database with PHP:

• From your PHP script, establish a connection to the MySQL server.

• If the connection is successful, create a database using SQL and save it in a string variable.

• Conduct the query successfully.

45. How will you upload the file in PHP?

By using the move_uploaded_file() function a file can be uploaded in PHP.

The syntax to upload the file is bool move_uploaded_file ( string $filename , string $destination )

46. Tell me how to download the file in PHP?

The readfile() function can be used to download the file in PHP.

Use this syntax to download the file in PHP.

int readfile ( string $filename )

47. When will the session end?

Sessions are automatically terminated when the PHP script completes execution, but they can also be terminated manually with the session_write_close().

48. Can you use the COM component in PHP?

Yes, (Distributed) Component Object Model components ((D)COM) can be used in PHP scripts that are provided as a framework.

49. What is the use of goto statements in PHP?

The goto statement can be used to jump around inside a PHP program. The instruction is defined as a goto statement followed by the desired target label, and the target is pointed to by a label followed by a colon.

50. How will you retrieve a cookie value?

Use this command to retrieve a value from the cookie.

echo $_COOKIE [“user”];

51. What do you mean by $GLOBALS?

$GLOBALS is an associative array that contains references to all variables currently described in the script’s global scope.

52. Tell us about $_SERVER?

The array $_SERVER contains information generated by the webserver, such as routes, headers, and script locations.

53. What is meant by $_FILES?

$_FILES is an associative array of objects sent through the HTTP POST method to the current script.

54. What do you mean by:: while accessing a class?

:: will access static methods that never require object initialization.

55. Which cryptographic extension allows you to create and verify digital signatures?

The PHP-OpenSSL extension supports a variety of cryptographic operations, including digital signature generation and verification.

The above-defined sets of questions are top-ranked PHP interview questions 2021.

FINAL WISHES BEFORE YOUR INTERVIEW:

We’ve reached the end of our PHP developer interview questions blog. I hope you find these PHP Interview Questions useful in your upcoming interviews. Land our course page on https://www.n-school.com/php-course/ and Check out our PHP & MySQL Certification Training at NSCHOOL Academy which includes instructor-led live training and real-world project experience, if you want to learn PHP development and develop your own web applications. We wish you all the best to crack the interview process!