40+ Senior PHP Developer Interview Questions and Answers

Functions are standalone blocks of code while methods are functions that belong to a class.

• Functions are defined outside of a class while methods are defined inside a class.

• Functions can be called directly while methods are called on an object of a class.

• Methods have access to the data and properties of the class while functions do not.

• Example of a function: function addNumbers($a, $b) { return $a + $b; }

• Example of a method: class Calculator { public function addNumbers($a, $...read more

To display an image from a database in a PHP view page, retrieve the image as a blob and output it with appropriate headers.

• Retrieve the image data from the database as a blob.

• Set the appropriate content-type header for the image format.

• Output the image data to the response body.

Group by is used to group rows based on a column, while distinct function is used to remove duplicate values from a column.

• Group by is used with aggregate functions like count, sum, avg, etc.

• Distinct function is used to retrieve unique values from a column.

• Group by can be used with multiple columns to create groups based on multiple criteria.

• Distinct function can be used with multiple columns to retrieve unique combinations of values.

• Group by is often used in conjunction with...read more

PHP is selected for web development due to its ease of use, flexibility, and large community support.

• PHP is easy to learn and use, making it accessible for beginners

• PHP is flexible and can be used for a variety of web development tasks

• PHP has a large community of developers who contribute to its development and provide support

• PHP is open source and free to use, making it a cost-effective option for web development

• PHP integrates well with other technologies, such as databases ...read more

The difference between $var and $$var is that $var is a variable with a fixed name, while $$var is a variable with a variable name.

• The $var variable is a regular variable with a fixed name, while $$var is a variable with a variable name.

• The $$var variable is also known as a variable variable.

• The value of $$var is determined by the value of $var.

• Example: $var = 'foo'; $$var = 'bar'; echo $foo; // Output: bar'

To fetch parents data from database whose name is searched.

• Use SQL query to fetch data from database

• Join parent table with child table using foreign key

• Use WHERE clause to filter data based on searched name

Composer is a dependency manager for PHP that simplifies the process of installing and managing third-party libraries.

• Composer allows developers to easily add external libraries to their PHP projects

• It manages dependencies and ensures that all required libraries are installed and up-to-date

• Composer uses a JSON file called 'composer.json' to define project dependencies

• It also provides a command-line interface for installing, updating, and removing dependencies

• Composer is widel...read more

PHP OOPs is a programming paradigm that uses objects and classes to organize code. Abstract classes provide partial implementation, while interfaces provide a contract for classes to implement. Index in MySQL is a data structure that improves the speed of data retrieval. GROUP BY is used to group rows that have the same values, while HAVING is used to filter groups based on a specified condition.

• PHP OOPs is a programming paradigm that uses objects and classes to organize code...read more

Variables can be changed during the execution of a script, while constants cannot be changed once they are defined.

• Variables can be reassigned with new values, while constants cannot be changed once defined

• Constants are defined using the define() function, while variables are assigned using the $ symbol

• Constants are case-sensitive by default, while variables are case-insensitive

Some basic PHP functions include echo, strlen, substr, array_push, and file_get_contents.

• echo - outputs one or more strings

• strlen - returns the length of a string

• substr - returns a part of a string

• array_push - adds one or more elements to the end of an array

• file_get_contents - reads the contents of a file into a string

The code will output 'Hello World!' because the variable $x is set to true.

• The code will check if $x is true, which it is, so it will output 'Hello World!'

• The if statement will only execute if the condition is true, in this case $x is true.

Different storage engines are used in databases to manage data storage and retrieval efficiently.

• InnoDB: ACID-compliant, supports transactions and foreign keys

• MyISAM: Fast and efficient for read-heavy workloads, no transaction support

• Memory: Stores data in memory for fast access, but data is lost on restart

• CSV: Stores data in CSV files, suitable for importing and exporting data

• Archive: Optimized for high compression, suitable for storing historical data

I have worked on various PHP frameworks including Laravel, CodeIgniter, and Symfony.

• Laravel - used for building web applications with elegant syntax and features like routing, authentication, and ORM

• CodeIgniter - lightweight framework with a small footprint and easy to learn

• Symfony - used for building complex web applications with reusable components and best practices

Interfaces in PHP define a contract for classes to implement certain methods, allowing for polymorphism and code reusability.

• Interfaces in PHP are used to define a set of methods that a class must implement.

• They allow for polymorphism, where different classes can implement the same interface but have different implementations for the methods.

• Interfaces promote code reusability by enforcing a common structure for classes that implement them.

• Interfaces can be used to create API...read more

TDD stands for Test-Driven Development. It is a software development process where tests are written before the actual code.

• Tests are written before writing the actual code

• Helps in defining the requirements and design of the code

• Ensures that the code meets the requirements and is working correctly

• Improves code quality and maintainability

• Examples: PHPUnit, Jest, Mocha

Yes, I have developed multiple PHP applications in the past.

• Developed a custom e-commerce website using PHP, MySQL, and JavaScript

• Created a content management system (CMS) using PHP and Laravel framework

• Built a web application for tracking employee attendance using PHP and Bootstrap

Design patterns are reusable solutions to common software development problems.

• Design patterns provide proven solutions to recurring problems in software development.

• They help in creating code that is more flexible, reusable, and maintainable.

• Some common design patterns include Singleton, Factory, Observer, and Decorator.

• Singleton pattern ensures that only one instance of a class is created.

• Factory pattern provides a way to create objects without specifying the exact class of...read more

Yes, PHP is a case sensitive language.

• Variable names are case sensitive

• Function names are case insensitive

• Constants are case sensitive

• Class names are case sensitive

Lumen Laravel is a lightweight micro-framework by Laravel for building fast and efficient APIs and microservices.

• Built by Laravel for creating APIs and microservices

• Lightweight and faster than Laravel

• Ideal for small projects or when performance is crucial

• Provides a subset of features compared to Laravel

A session in PHP is a way to store information (variables) to be used across multiple pages.

• Sessions are used to store user data on the server for later use

• Sessions are identified by a unique session ID, usually stored in a cookie

• Session data is stored on the server side, making it more secure than using cookies alone

CSRF token is used to protect against Cross-Site Request Forgery attacks in Laravel.

• CSRF token is a unique token generated for each user session.

• It is added to forms or AJAX requests to verify the authenticity of the request.

• Laravel automatically generates and verifies CSRF tokens for each request.

• CSRF tokens can be added to forms using the @csrf Blade directive.

• CSRF tokens can be added to AJAX requests using the X-CSRF-TOKEN header or a meta tag.

PHP program to sort array of strings

• Use the built-in sort() function

• Pass the array as argument to the sort() function

• Use the SORT_STRING flag to sort the array as strings

Laravel is a modern PHP framework with elegant syntax and CodeIgniter is a lightweight PHP framework with a small footprint.

• Laravel has a more expressive syntax and provides more features out of the box

• CodeIgniter is faster and has a smaller learning curve

• Laravel has a built-in ORM called Eloquent while CodeIgniter uses Active Record

• Laravel has a better community support and documentation compared to CodeIgniter

Mysql Joins are used to combine rows from two or more tables based on a related column between them.

• Types of Mysql Joins include INNER JOIN, LEFT JOIN, RIGHT JOIN, and FULL JOIN.

• INNER JOIN returns rows when there is at least one match in both tables.

• LEFT JOIN returns all rows from the left table and the matched rows from the right table.

• RIGHT JOIN returns all rows from the right table and the matched rows from the left table.

• FULL JOIN returns rows when there is a match in one...read more

ORM is a programming technique for converting data between incompatible type systems in object-oriented programming languages.

• ORM simplifies data manipulation by allowing developers to work with objects instead of database tables directly.

• ORM reduces the amount of repetitive SQL code that needs to be written.

• ORM can help improve code readability and maintainability by abstracting database interactions.

• Popular PHP ORM frameworks include Doctrine, Eloquent (Laravel), and Propel...read more

Natarajan Chandrasekaran is the current chairman of Tata Group.

• Natarajan Chandrasekaran is the chairman of Tata Sons, the holding company of Tata Group.

• He took over as chairman in 2017, succeeding Cyrus Mistry.

• Chandrasekaran has been with the Tata Group since 1987, starting his career at Tata Consultancy Services (TCS).

Instance variable is a variable that is associated with a specific instance of a class, rather than with the class itself.

• Instance variables are declared within a class but outside of any method.

• They hold data that is unique to each instance of the class.

• Example: In a class representing a car, 'color' could be an instance variable that stores the color of each individual car object.

Dependency Injection is a design pattern in which a class receives its dependencies from external sources rather than creating them itself.

• Allows for better code reusability and testability

• Promotes loose coupling between classes

• Dependencies are injected into a class through constructor injection, setter injection, or interface injection

Reverse routing is the process of generating a URL based on a route name and parameters.

• Reverse routing helps in generating URLs dynamically based on route names and parameters

• It allows for cleaner and more maintainable code by decoupling URLs from the code

• Example: Generating a URL for a specific route like 'blog.post' with parameters like post ID

REST API is a standard for communication between systems, with authorization ensuring only authorized users can access resources.

• REST API uses HTTP methods like GET, POST, PUT, DELETE to interact with resources

• Authorization can be implemented using tokens like JWT or OAuth

• Access control lists (ACL) can be used to define permissions for different users or roles

Optimisation techniques for PHP development

• Use caching mechanisms like Memcached or Redis to reduce database load

• Minify and concatenate CSS and JS files to reduce loading time

• Optimize database queries by using indexes and avoiding unnecessary joins

• Implement lazy loading for images and resources to improve page load speed

Cookies are stored on the client side, while sessions are stored on the server side.

• Cookies are stored on the client's browser, while sessions are stored on the server.

• Cookies can be set to expire at a specific time, while sessions typically expire when the browser is closed.

• Cookies can be accessed by both the client and server, while sessions are only accessible by the server.

• Cookies are limited in size (usually 4KB), while sessions can store larger amounts of data.

• Example: ...read more

I prefer TCS for its global presence, diverse projects, and opportunities for growth.

• TCS has a strong global presence with offices in multiple countries.

• TCS offers a wide range of projects in various industries, providing valuable experience.

• TCS provides opportunities for career growth and skill development through training programs and certifications.

MVC design pattern separates application logic into three components: Model, View, and Controller.

• Model represents the data and business logic of the application.

• View is responsible for displaying the data to the user.

• Controller acts as an intermediary between Model and View, handling user input and updating the Model accordingly.

• Example: Laravel, CodeIgniter, Symfony are PHP frameworks that follow MVC pattern.

Inheritance is a concept in object-oriented programming where a class inherits attributes and methods from another class.

• Allows a class to inherit properties and methods from another class

• Promotes code reusability and reduces redundancy

• Creates a parent-child relationship between classes

I have successfully completed multiple projects in my career as a Senior PHP Developer.

• Developed a custom e-commerce platform for a client using PHP, MySQL, and JavaScript.

• Implemented RESTful APIs for a mobile application using PHP and Laravel framework.

• Optimized website performance by refactoring code and implementing caching techniques.

PHP array functions are built-in functions in PHP that allow manipulation of arrays.

• Some common PHP array functions include array_push(), array_pop(), array_merge(), array_filter(), and array_map().

• array_push() adds one or more elements to the end of an array.

• array_pop() removes and returns the last element of an array.

• array_merge() merges one or more arrays into a single array.

• array_filter() filters elements of an array using a callback function.

• array_map() applies a callbac...read more