200+ PHP Developer Interview Questions and Answers

HTML is a markup language used for creating web pages. Python is a high-level programming language known for its simplicity and readability.

• HTML stands for HyperText Markup Language and is used to create the structure of web pages.

• Python is a versatile programming language known for its clean syntax and ease of use.

• HTML uses tags to define elements on a web page, such as headings, paragraphs, and images.

• Python is often used for web development, data analysis, artificial intel...read more

Abstract classes and interfaces are used to define common methods and properties for classes to implement.

• Abstract classes cannot be instantiated and can contain both abstract and non-abstract methods.

• Interfaces only contain method signatures and constants, and classes can implement multiple interfaces.

• Abstract classes are useful for creating a base class with common functionality, while interfaces are useful for defining a contract for classes to follow.

• Example: abstract cla...read more

Exceptions can be handled using try-catch blocks in PHP.

• Use try-catch blocks to enclose the code that may throw an exception.

• Catch the exception using catch block and handle it appropriately.

• Multiple catch blocks can be used to handle different types of exceptions.

• Finally block can be used to execute code regardless of whether an exception occurred or not.

include() includes and evaluates a specified file, while include_once() does the same but ensures the file is only included once.

• include() can include the same file multiple times, while include_once() will only include it once

• include() will continue to execute the script even if the file is not found, while include_once() will throw a warning and continue

• include_once() is useful for preventing multiple declarations of functions or classes

Helpers in CodeIgniter are utility functions that assist in common tasks and can be used throughout the application.

• Helpers are standalone functions that can be loaded and used anywhere in the application.

• They provide a way to avoid writing repetitive code by providing ready-to-use functions.

• CodeIgniter comes with a set of built-in helpers, such as URL, Form, File, and Date helpers.

• Custom helpers can also be created to extend the functionality of the framework.

• Helpers are loa...read more

JavaScript is a programming language used for client-side scripting, while jQuery is a library built on top of JavaScript.

• JavaScript is a programming language that allows you to create dynamic web content and interact with the user.

• jQuery is a library that simplifies JavaScript programming by providing pre-written functions and methods.

• JavaScript is a core language, while jQuery is a framework built on top of JavaScript.

• JavaScript can be used for a wide range of tasks, includ...read more

JS vs jQuery, CRUD query, require() vs include()

• JavaScript is a programming language while jQuery is a library built on top of it

• CRUD operations can be performed using AJAX in both JS and jQuery

• require() is used in Node.js to import modules while include() is used in PHP

To fetch data from database, use SELECT statement. To insert data into database, use INSERT statement.

• Use SELECT statement with appropriate conditions to fetch data from database

• Use INSERT statement with appropriate values to insert data into database

• Make sure to sanitize user inputs to prevent SQL injection attacks

Padding is the space inside an element, while margin is the space outside an element.

• Padding is used to create space between the content and the border of an element.

• Margin is used to create space between elements or between an element and its parent.

• Padding affects the size of the content area, while margin affects the positioning of the element.

• Padding is transparent and does not have a background color, while margin can have a background color.

A program to determine valid parenthesis

• Use a stack data structure to keep track of opening parenthesis

• Iterate through the string and push opening parenthesis onto the stack

• If a closing parenthesis is encountered, check if the stack is empty or the top element is not the corresponding opening parenthesis

• If the stack is empty or the top element is not the corresponding opening parenthesis, the string has invalid parenthesis

• After iterating through the string, if the stack is em...read more

Sessions and cookies are used to store and retrieve data in web applications.

• Sessions are used to store data on the server side and are identified by a unique session ID.

• Cookies are used to store data on the client side and are stored as small text files.

• Sessions are more secure as the data is stored on the server, while cookies can be manipulated by the client.

• Sessions are typically used to store sensitive information like user login details, while cookies are used for perso...read more

Middleware is software that acts as a bridge between an application and the server, handling requests and responses.

• Middleware can modify incoming requests before they reach the application.

• It can also modify outgoing responses before they are sent back to the client.

• Types of middleware include authentication middleware, logging middleware, error handling middleware, etc.

• Examples of middleware in PHP frameworks include Laravel's middleware for authentication and authorization...read more

Creating, inserting, updating, and deleting data in a database using PHP.

• Create a database connection using PHP's mysqli or PDO extension

• Use SQL queries to create tables, insert data, update data, and delete data

• Example: CREATE TABLE users (id INT AUTO_INCREMENT PRIMARY KEY, name VARCHAR(50), email VARCHAR(50));

• Example: INSERT INTO users (name, email) VALUES ('John Doe', 'john.doe@example.com');

• Example: UPDATE users SET email = 'johndoe@example.com' WHERE id = 1;

• Example: DELE...read more

Creating a database and inserting data using SQL queries.

• Create a database using CREATE DATABASE statement

• Use INSERT INTO statement to add data to the database

• Ensure proper data types and constraints are defined

Primary key uniquely identifies a record while secondary key is used for data retrieval and sorting.

• Primary key is a unique identifier for a record in a table.

• Secondary key is used for data retrieval and sorting.

• A table can have only one primary key but multiple secondary keys.

• Primary key cannot have null values while secondary key can have null values.

• Primary key is automatically indexed while secondary key needs to be indexed manually.

Session management for payment gateway

• Use secure HTTPS connection for communication

• Store sensitive data in encrypted format

• Set session timeout to a short duration

• Use unique session IDs for each transaction

• Destroy session after successful payment or on timeout

I have 5 years of experience as a PHP Developer with expertise in various technologies. My goal is to continue growing in my career.

• 5 years of experience as a PHP Developer

• Proficient in various technologies such as PHP, MySQL, HTML, CSS, JavaScript

• Worked on multiple projects, including e-commerce websites and content management systems

• Continuously learning and staying updated with the latest trends and advancements in PHP development

• Goal is to further enhance my skills and co...read more

I am interested in Bridcodes because of their innovative projects and the opportunity to work with cutting-edge technologies.

• Exciting projects that push boundaries

• Opportunity to work with new technologies like Laravel and Vue.js

• Positive company culture and growth opportunities

Definitions of key concepts in PHP development

• Constructor: Special method used to initialize objects in a class

• Magic methods: Predefined methods in PHP classes that start with __

• Static methods: Methods that can be called without instantiating a class

• Abstract class: Class that cannot be instantiated and may contain abstract methods

• Traits: Reusable code that can be included in multiple classes

• Namespace: A way to organize code by grouping related classes, interfaces, functions, ...read more

The default join in MySQL is INNER JOIN.

• INNER JOIN is the most commonly used join in MySQL.

• It returns only the matching rows from both tables.

• Other types of joins include LEFT JOIN, RIGHT JOIN, and FULL OUTER JOIN.

Array functions in PHP are used to manipulate arrays in various ways.

• 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_slice() - extracts a slice of an array

• array_search() - searches an array for a specific value and returns the corresponding key if successful

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

• Inheritance allows a class to reuse code from another class.

• There are different types of inheritance: single inheritance, multiple inheritance, multilevel inheritance, and hierarchical inheritance.

• Example: Class B inherits from Class A, so Class B can access all the properties and methods of Class A.

Reverse the name and shift the printed numbers based on even and odd positions.

• Reverse the name: 'John Doe' becomes 'eoD nhoJ'

• Shift the table printed numbers based on even and odd positions

• For example, if the table printed numbers are 1, 2, 3, 4, 5, the shifted numbers would be 2, 1, 4, 3, 5

GET and POST are HTTP methods used to send data to a server. GET appends data to the URL while POST sends it in the request body.

• GET is used for retrieving data from a server while POST is used for submitting data to a server.

• GET appends data to the URL as query parameters while POST sends it in the request body.

• GET requests can be bookmarked and cached while POST requests cannot.

• GET requests have length restrictions while POST requests do not.

• GET requests are less secure as ...read more

unset and unlink are functions in PHP used to remove variables and files respectively.

• unset is used to destroy a variable and free up memory

• unlink is used to delete a file from the server

• Both functions return a boolean value indicating success or failure

• unset can be used on arrays, objects, and variables

• unlink can be used with a file path or a file handle

Data can be sent from one page to another using methods like GET, POST, SESSION, COOKIES, and AJAX.

• Use GET method to send data through URL parameters

• Use POST method to send data through form submissions

• Use SESSION to store data temporarily across multiple pages

• Use COOKIES to store data on the client side

• Use AJAX to send data asynchronously without reloading the page

PHP is advantageous over Dot net and JAVA due to its simplicity, flexibility, and cost-effectiveness.

• PHP is open-source and free to use, while Dot net and JAVA require licenses.

• PHP is easy to learn and has a low barrier to entry compared to Dot net and JAVA.

• PHP is platform-independent, allowing for greater flexibility in deployment.

• PHP has a large community and extensive documentation for support and resources.

Sort an array in PHP without using any function.

• Use a sorting algorithm like bubble sort or insertion sort.

• Iterate through the array and compare adjacent elements to swap them if necessary.

• Repeat the process until the array is sorted.

Slice is used to extract a portion of an array without modifying the original array, while splice is used to add or remove elements from an array.

• Slice returns a shallow copy of a portion of an array into a new array without modifying the original array.

• Splice changes the contents of an array by removing or replacing existing elements or adding new elements in place.

• Example: let arr = [1, 2, 3, 4, 5]; arr.slice(1, 3) will return [2, 3] while arr.splice(1, 2) will modify arr t...read more

Encapsulation, polymorphism, and abstraction are key concepts in object-oriented programming.

• Encapsulation is the bundling of data and methods that operate on that data into a single unit. It helps in data hiding and prevents direct access to data.

• Polymorphism allows objects of different classes to be treated as objects of a common superclass. It enables flexibility and reusability in code.

• Abstraction involves hiding the complex implementation details and showing only the nec...read more

Understanding the client's needs, providing quality service, clear communication, and building a strong relationship are important for a client.

• Understanding the client's requirements and expectations

• Providing high quality service or product

• Maintaining clear and open communication

• Building a strong and trusting relationship with the client

Candidate key uniquely identifies a record in a table, while foreign key establishes a relationship between two tables.

• Candidate key is a unique key that can be used to uniquely identify a record in a table.

• Foreign key is a key that establishes a relationship between two tables.

• Candidate key can be a primary key or a unique key, while foreign key references a primary key in another table.

• Example: In a 'students' table, 'student_id' can be a candidate key, while 'department_id...read more

SQL query to find the third highest salary from employees table.

• Use the ORDER BY clause to sort salaries in descending order.

• Use the LIMIT clause to retrieve the third highest salary.

• Consider handling cases where there may be ties for the third highest salary.

The time taken to build a complete website varies depending on the complexity and requirements of the project.

• The time can range from a few days for a simple website to several months for a complex e-commerce platform.

• Factors such as design complexity, functionality, integration of third-party services, and testing can impact the development time.

• Using frameworks like Laravel or Symfony can speed up development process compared to building from scratch.

• Collaboration with a te...read more

Arrays and objects are data structures used in programming to store multiple values or properties.

• Arrays are ordered collections of values accessed by index.

• Objects are collections of key-value pairs where values are accessed by keys.

• Example of array: $colors = ['red', 'blue', 'green'];

• Example of object: $person = ['name' => 'John', 'age' => 30];

Keys and joins are important concepts in SQL for relating tables and retrieving data based on relationships.

• Keys in SQL are used to uniquely identify records in a table. Primary keys are used to uniquely identify each record in a table, while foreign keys are used to establish relationships between tables.

• Joins in SQL are used to combine rows from two or more tables based on a related column between them. Common types of joins include INNER JOIN, LEFT JOIN, RIGHT JOIN, and FU...read more

Indexing, triggers, and stored procedures are database concepts used to optimize performance and automate tasks.

• Indexing is a technique used to improve the speed of data retrieval operations in a database by creating indexes on columns.

• Triggers are special types of stored procedures that are automatically executed in response to certain events on a table, such as insert, update, or delete operations.

• Stored procedures are precompiled SQL statements that are stored in the datab...read more

Unlink is used to delete a file from the filesystem, while unset is used to unset a variable.

• Unlink is used to delete a file from the filesystem in PHP.

• Unset is used to unset a variable in PHP.

• Unlink requires the file path as an argument, while unset requires the variable name.

Namespaces are used to avoid naming conflicts between classes, functions, and variables, while class names are used to define blueprints for objects.

• Namespaces are used to organize code into logical groups, preventing naming collisions.

• Class names define blueprints for objects and can be instantiated to create objects.

• Namespaces can be nested within each other, while classes cannot be nested.

• Namespaces are declared using the 'namespace' keyword, while classes are declared usi...read more

The logical flowchart of a project outlines the steps involved in its development. Various development methods can be used.

• Identify project requirements and objectives

• Create a flowchart to outline the logical steps involved in the project

• Choose a development method such as Agile or Waterfall

• Implement the project using the chosen method

• Test and debug the project

• Deploy the project and maintain it

Ajax can be used to upload files without refreshing the page.

• Create a form with file input and submit button.

• Use FormData object to collect form data.

• Send data to server using Ajax.

• Handle file upload on server side.

• Return response to client and update UI.

To reverse a list in Python, you can use the built-in reverse() method or slicing technique.

• Use the reverse() method to reverse the list in place: list.reverse()

• Use slicing to create a new reversed list: reversed_list = list[::-1]

Commands in Laravel are artisan commands that help developers perform various tasks such as database migrations, seeding, and creating controllers.

• Artisan commands are run through the command line interface using the 'php artisan' command.

• Some common artisan commands include 'php artisan migrate' for running database migrations, 'php artisan db:seed' for seeding the database with dummy data, and 'php artisan make:controller' for creating a new controller.

• Developers can also c...read more

Eloquent ORM is an advanced PHP implementation of the Active Record pattern for working with databases.

• Eloquent ORM is included with the Laravel PHP framework.

• It allows developers to interact with databases using PHP objects instead of writing SQL queries.

• Eloquent models represent database tables and can be used to perform CRUD operations.

• Relationships between database tables can be defined using Eloquent's model relationships.

MVC is a software architectural pattern that separates an application into three main 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 handles user input, updates the model, and interacts with the view.

• MVC promotes separation of concerns and improves code organization and maintainability.

• Example: In a PHP web application, the model could be a class that in...read more

Array types and functions

• PHP arrays can store multiple values of different types

• Arrays can be indexed numerically or with strings

• Common array functions include count(), sort(), and array_push()

• Example: $fruits = ['apple', 'banana', 'orange'];

An autoloader is a function that automatically loads classes when they are needed in a PHP script.

• Autoloaders eliminate the need to manually include class files.

• They use naming conventions to locate and load class files.

• Autoloaders can be registered using spl_autoload_register() function.

• Composer provides a default autoloader for PHP projects.