PHP Interview Questions And Answers

PHP (Hypertext Preprocessor) is a ubiquitous programming language utilized for server-side scripting. It is one of the most widely used scripting languages for creating dynamic websites and applications. Because of its faster and more extensive features, PHP is used in developing various large-scale applications such as Tumblr, MailChimp, Slack, WordPress, and Facebook, which are prominent examples of PHP applications.

If you want to become a PHP developer, preparing for the interview is very important, which is conducted to see the skills and knowledge of the candidate. In this blog, we have put together a set of basic, intermediate, and hard PHP questions that cover a wide range of topics and concepts of PHP. Knowing these interview questions can help you crack your next job interview.

Basic PHP Interview Questions

What is PHP?

PHP stands for “Hypertext preprocessor.” It is an open-source interpreter language that is used for server-side scripting, which means the web server runs the PHP code before redirecting the page to the browser. It supports cross-platform functionality, which means it can work on various platforms like Windows, Linux, and MacOS.

What does PEAR stand for?

PEAR is known as PHP Extension and Application Repository, a framework or repository for reusable PHP components. This framework provides a structured library that is used to help developers write code that can be reused. It also provides a command-line interface to install packages from databases and networks automatically.

What are the popular frameworks in PHP?

A PHP framework is a collection of pre-built tools for developing web applications. Here are some frameworks of PHP:

Laravel
CakePHP
CodeIgniter
Symphony
Yii
Laminas

What are the benefits of using PHP over other scripting languages?

PHP is a robust and open-source scripting language, making it reliable in comparison to other scripting languages like Python and JavaScript. Here are some benefits of using PHP over Python and JavaScript:

Syntax: the syntax of PHP is simple, like C, which is easy to use and learn.
Usage: PHP is mainly used for backend development, while Python is used for broad applications embedded with AI, and JavaScript is used for front-end development.
Cost-effective: Its free and open-source feature makes it a cost-effective option.

What are the data types of PHP?

PHP supports a wide range of data types, including:

Scalar Data Types

Integer: Whole Numbers (e.g. $num = 150; )

String: Textual data (i.e. $name = “Salar”; )

Float: Decimal Numbers (i.e. $cost = 5.78; )

Boolean: True and False (i.e. $isFruit = true; )

Compound Data Types:

Array: Collection of homogenous values (i.e. $things = array(“chair”, “table”);

Class: A group of objects

Object: Instance of class

Special Data Types:

Null: Variable with no value

Resource: Reference to function

Intermediate PHP Interview Questions

What is a PHP session, and how is it different from cookies?

PHP sessions are used to store user-related information on the server across multiple pages of the website. A session allows computers to know when the application is started and closed by the user, and the session expires when the user logs out of the application (session_start()). Unlike cookies, which store data on the browser such as usernames and passwords to identify the user, they also have an expiration date (setcookie(“user”, “karry”, time()+2400);).

What is the difference between GET and POST methods?

POST: Sends data in the form of a request body, which is invisible to the user. The method makes data secure and ideal for login credentials and form submission.

GET: Sends data in the form of a formatted URL, making it visible in the address bar. The method is used for retrieving data like search queries.

What is the difference between echo and print?

Echo and print both work similarly; used to output data in PHP. But there is a slight difference between both:

Echo is faster and can take multiple parameters separated by commas (echo “Hello,” “World”);.

Print can output a single string and return value 1, making it slower than echo (print “Hello”);.

What is a PHP function, and how do you create it?

A function in PHP is a block of code used to perform a specific task and return the results. A PHP function is a standalone type, which means you don’t need to write the function or anything. PHP offers various built-in functions, and users can also define their own functions. You can create a function like this:

function statement(); {

Print ("My first program”);

}

What are super globals?

Superglobals are pre-defined variables that are available globally and accessible from all scopes. Examples:

$_GET: Collects data from HTML form and retrieves URL parameters.

$_POST: Collects form data submitted via POST, and the form uses the method GET to transfer data.

$_SESSION: Store session variables like the opening and closing time of an application.

$_COOKIE: Retrieves cookie values like form credentials.

$_FILES: Handling file uploaded via HTTP post methods.
$_SERVER: Provides information on server and execution environment.

$_REQUEST: Collects requested data from both GET and POSt methods.

Advanced PHP Interview Questions

How do you integrate PHP scripts into an HTML page?

To connect PHP code to an HTML file, we need to use the (.php) file extension, which allows the server to send the file to PHP for processing.

<?php

            // PHP code

?>

What is the Include and Require function?

Include(): The function is used to insert all the content of a specified file within the function at the point where the “include” statement is written. The include function includes no-critical files and executes if errors accrue or the system fails.

Require(): The require() function works the same as the include() function; it copies the code within the file where the require function is called. The function includes critical files and terminates the script if an error occurs.

How do you connect PHP code to a MySQL database?

Here is the code to connect PHP code to a database in two ways: MySQLi or PDO (PHP data objects):

Using MySQLi:

$mysqli = new mysqli("localhost", "username", "password", "database");

if ($mysqli->connect_error) {

    die("Connection failed: " . $mysqli->connect_error);

}

Using PDO:

$dsn = "MySQL:host=localhost;dbname=testdb";

$user = "username";

$pass = "password";

$pdo = new PDO($dsn, $user, $pass);

What is a composer in PHP?

Composer is a dependency management tool for PHP that helps install and manage libraries and packages. It allows third-party libraries or code to integrate with your website and application, whenever needed. For accessing libraries and code, run this syntax:

Composers require vendor/package

What are the error-handling techniques in PHP?

Error handling is an essential part of writing a script for creating a web application. Here are some error-handling methods:

Using the die() function: The die() function prints a message instead of showing errors and exists from the script.

<?php

           // php code

           // the file is not present 

If ( !file-exists (“file.txt”)) {

     Die (“ file not exist”);

}

Else {                           // If file presents

$file = fopen (“file.txt”, “w”);       

}

?>

Using custom error handling: Creating a custom error handler is a simple process that is called when an error occurs. Such as: myerror( $error_no, $error_msg)

Conclusion:

PHP is an indispensable and widely used programming language, making it essential for creating dynamic web pages. It is not only for professionals—even beginners can also utilize this efficient language to create their websites and applications. By preparing these questions, you can boost your confidence and land your dream of being a PHP developer.

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