200+ PHP Developer Interview Questions and Answers

PHP is a server-side scripting language designed for web development, enabling dynamic content generation and database integration.

• Server-side Scripting: PHP code runs on the server, generating HTML output for the client, enhancing security and performance.

• Dynamic Content: PHP can create dynamic web pages by retrieving and displaying data from databases, such as user profiles or product listings.

• Database Integration: PHP supports various databases like MySQL and PostgreSQL, m...read more

Errors can be reported in log files using error_log() function in PHP.

• Use error_log() function to log errors in a file

• Specify the error message and the log file path as parameters

• Example: error_log('Error message', 3, '/var/log/php_errors.log')

• Use error_reporting() function to set the level of error reporting

There are three types of errors in PHP: syntax errors, runtime errors, and logical errors.

• Syntax errors occur when the code violates the rules of PHP syntax.

• Runtime errors occur during the execution of the script, such as division by zero or accessing undefined variables.

• Logical errors do not cause the script to terminate, but they produce incorrect results or unexpected behavior.

Rotate array elements based on number of loops specified.

• Create a new array by slicing the original array based on the number of loops specified.

• Concatenate the sliced array with the remaining elements of the original array.

• Handle edge cases where the number of loops is greater than the array length by using modulo operator.

Group by and having are used to group data and filter groups based on conditions.

• Group by is used to group data based on a specific column or expression.

• Having is used to filter groups based on conditions.

• Sample query: SELECT column1, COUNT(column2) FROM table GROUP BY column1 HAVING COUNT(column2) > 10;

PHP has over 100 array functions and over 200 string functions.

• Array functions include: array_push(), array_pop(), array_merge(), array_slice(), etc.

• String functions include: strlen(), str_replace(), substr(), strtolower(), etc.

• PHP also has functions for working with regular expressions, dates, and more.

• The exact number of functions may vary depending on the version of PHP being used.

A join query combines rows from two or more tables based on a related column.

• Use INNER JOIN to select records with matching values in both tables.

• Example: SELECT * FROM users INNER JOIN orders ON users.id = orders.user_id;

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

• Example: SELECT * FROM users LEFT JOIN orders ON users.id = orders.user_id;

• RIGHT JOIN returns all records from the right table and matched records from the left table....read more

DBMS is a software system that manages databases, RDBMS is a type of DBMS that stores data in a structured format, ODBMS is a type of DBMS that stores data in an object-oriented manner.

• DBMS (Database Management System) is a software system that allows users to interact with a database. Examples include MySQL, Oracle, SQL Server.

• RDBMS (Relational Database Management System) is a type of DBMS that stores data in tables with rows and columns. Examples include MySQL, PostgreSQL, ...read more

Yes, I have experience implementing multiple-domain sub-domain systems. I have used this approach in previous projects for better organization and scalability.

• Implemented multiple-domain sub-domain system for better organization and scalability

• Used sub-domains to separate different sections or functionalities of the product

• Helps in managing different domains under a single codebase

• Improves SEO by having separate sub-domains for different content

Yes, I have experience implementing shipping APIs in previous projects.

• I have integrated shipping APIs in e-commerce websites to automate shipping calculations and tracking.

• I have used shipping APIs from providers like UPS, FedEx, and USPS to provide accurate shipping rates to customers.

• I have customized shipping API implementations to suit the specific needs of the project, such as handling international shipping or special delivery options.

MVC is a software design pattern that separates an application into three interconnected components: Model, View, and Controller.

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

• View is responsible for rendering the user interface.

• Controller handles user input and updates the model and view accordingly.

• Library is a collection of pre-written code that can be reused in different projects.

• Helper function is a function that performs a specific task and can be calle...read more

Echo and print are both used to output data in PHP, but echo is slightly faster and can take multiple arguments.

• Echo is a language construct, while print is a function.

• Echo does not return a value, while print returns 1.

• Echo can output multiple strings separated by commas, while print can only output one string.

• Echo is generally preferred for performance reasons.

Javascript object is a data structure while JSON is a data interchange format.

• Javascript object is used to store and manipulate data within a program.

• JSON is used to exchange data between different programs and systems.

• Javascript object can have methods and functions while JSON cannot.

• Javascript object can have circular references while JSON cannot.

• JSON is a subset of Javascript object notation.

Use a MySQL query to select data with employee name, code, and their manager using manager_id as foreign key.

• Use JOIN to connect the employee and manager tables based on the manager_id foreign key

• Select the employee name, code, and manager's name using appropriate aliases

• Make sure to specify the table names and columns correctly in the query

Multiple inheritance allows a class to inherit from multiple parent classes, while multilevel inheritance involves a chain of inheritance.

• Multiple inheritance allows a class to inherit from more than one parent class.

• Multilevel inheritance involves a chain of inheritance, where a class inherits from another class, which in turn inherits from another class.

• In multiple inheritance, a class can inherit attributes and methods from multiple parent classes.

• In multilevel inheritance...read more

Middleware in Laravel is a mechanism that allows filtering HTTP requests entering your application.

• Middleware can be used to authenticate users, authorize access, handle CORS, log requests, etc.

• Middleware can be applied globally to all routes or specific to certain routes or groups of routes.

• To create a middleware, use the `make:middleware` Artisan command.

• Middleware can be registered in the `app/Http/Kernel.php` file.

• Middleware can be assigned to routes using the `middleware...read more

Questions related to PHP development including cookies, sessions, CSS, database connection, and form design.

• Cookies are small text files stored on the client-side to remember user information.

• Sessions are server-side data storage to maintain user information across multiple pages.

• CSS can be used to style HTML elements side by side using the display property.

• To retrieve a column from a database using PHP, use the SELECT statement in SQL.

• While loop is used in PHP for repetitive...read more

Closures are anonymous functions that can be assigned to a variable and used as a callback function.

• Closures are used to create functions that can be passed as arguments to other functions.

• They can access variables outside of their scope, making them useful for creating flexible and reusable code.

• Closures are often used in event handling, asynchronous programming, and functional programming.

• Example: $add = function($a, $b) { return $a + $b; };

• Example: usort($array, function($...read more

Answers to common PHP developer interview questions

• Session is a way to store user data on the server side

• Triggers are used to execute a set of SQL statements when a specific event occurs

• Views are virtual tables that display data from one or more tables

• Array functions include array_push, array_pop, array_merge, and more

• GET and POST are HTTP methods used to send data to a server

• Abstract classes cannot be instantiated and are used as templates for other classes

• Function overloadi...read more

The output of a PHP program using And and Or depends on the logic used in the program.

• And (&&) returns true if both conditions are true

• Or (||) returns true if at least one condition is true

• The output will depend on the logic used in the program

Transitioned to PHP for its widespread use in web development and job opportunities.

• PHP is widely used in web development, offering more job opportunities compared to Java and C++.

• PHP is known for its simplicity and ease of use, making it a popular choice for web development projects.

• Transitioning to PHP allows me to broaden my skill set and stay current with industry trends.

array_merge merges two or more arrays into one, while array_combine creates an array by using one array for keys and another for its values.

• array_merge combines the values of two or more arrays into a single array

• array_combine creates an array using one array for keys and another for its values

• array_merge preserves numeric keys, while array_combine uses the first array for keys and the second for values

• array_merge can merge arrays with non-numeric keys, while array_combine re...read more

I chose to work with PHP because of its simplicity, flexibility, and large community support.

• PHP is easier to learn and use compared to Java, making it more accessible for beginners.

• PHP is widely used for web development, which aligns with my career goals.

• PHP has a large community of developers and resources available online for support and learning.

• PHP is known for its flexibility and ability to integrate with various databases and frameworks.

• PHP allows for rapid development...read more

Cookies store data on client-side while sessions store data on server-side.

• Cookies are vulnerable to cross-site scripting (XSS) attacks while sessions are not.

• Cookies can be tampered with by the client while sessions cannot.

• Sessions are more secure as they do not expose sensitive data to the client.

• Cookies have an expiration time while sessions expire when the user closes the browser.

• Sessions are preferred for sensitive data while cookies are preferred for non-sensitive data.

There are three main types of errors in PHP: syntax errors, runtime errors, and logical errors.

• Syntax errors occur when there is a mistake in the code that prevents it from being parsed correctly by the PHP engine. For example, missing semicolons or parentheses.

• Runtime errors occur during the execution of the code, such as division by zero or calling a function that does not exist.

• Logical errors occur when the code runs without any syntax or runtime errors, but does not produ...read more

Laravel follows a series of steps to handle a request and generate a response.

• The request is first received by the web server and passed to the index.php file in the public directory.

• The index.php file loads the Laravel framework and creates an instance of the application.

• The application then handles the request by routing it to the appropriate controller method.

• The controller method processes the request and returns a response.

• The response is then sent back to the web server...read more

Ajax stands for Asynchronous JavaScript and XML. It is a technique used for creating fast and dynamic web pages.

• Ajax allows web pages to be updated asynchronously by exchanging small amounts of data with the server behind the scenes.

• It uses XMLHttpRequest object to communicate with the server.

• Ajax can be used to update parts of a web page without reloading the entire page.

• There are multiple attributes in Ajax such as url, type, data, success, error, etc.