1. What are the advantages of using PHP?

• PHP is an Open-source, making it free to use and accessible to wide range of developers

• PHP offers abundant resources, frameworks, plugins, and libraries.

• PHP runs on various operating systems (Windows, Linux, macOS) and works seamlessly with most web servers (Apache, Nginx, IIS).

• PHP easily connects with both relational and non-relational databases

• PHP supports both small-scale projects and large-scale enterprise applications. Frameworks like Laravel and Symfony enhance scalability.

• PHP allows developers to build dynamic and interactive websites with ease, using features like session management, form handling, and cookie management.

2. What are the use-cases of PHP?

• PHP powers popular Content Management Systems ( CMS ) like WordPress, Drupal and Joomla.

• PHP is used for building e-commerce platforms like WooCommerce via WordPress

• PHP frameworks like Laravel, Symfony, and Yii are ideal for developing Social media platforms, Online booking systems, and Learning management systems.

• PHP is widely used for creating dynamic websites that require frequent content updates and user interactions.

• With frameworks like Slim and Lumen, PHP is used to create lightweight RESTful APIs.

• PHP is often used to collect data from forms and generate reports in various formats (PDF, CSV, etc.).

3. What are the main differences between PHP and other server-side languages like Python or Ruby?

a. Performance:

• PHP: Fast for web applications, especially with PHP 8 optimizations.

• Python: Slower but excels in compute-intensive tasks.

• Ruby: Slower, prioritizes developer productivity.

b. Ecosystem:

• PHP: Rich in web frameworks (Laravel, WordPress).

• Python: Broad library support for web, AI, and beyond.

• Ruby: Focused on Ruby on Rails for web apps.

c. Deployment:

• PHP: Widely supported by shared hosting and easy to deploy.

• Python: Requires specialized hosting or containers.

• Ruby: Often needs dedicated environments like Passenger.

4. What is the purpose of the isset() and unset() functions?

a. isset()

• Purpose: Checks if a variable is set and not null.

• Usage: Determines whether a variable exists and has a value other than null. Often used to check if form data, session variables, or other inputs are set.

• Example:

$var = “Hello”;
If(isset($var)){
echo “Variable is set and not null.”;
}

Output: Variable is set and not null.

b. unset()

• Purpose: Destroys a variable or unsets its value.

• Usage: Removes the variable from memory, making it undefined. Can also unset array elements or object properties.

• Example:

$var = “Goodbye”;
unset($var);
if(!isset($var)){
echo “Variable has been unset.”;
}

Output: Variable has been unset.

5. How do you handle sessions in PHP?

• Use session_start()at the beginning of the script.

• Use $_SESSION to store session variables.

• Retrieve session data from $_SESSION.

• Update session variables directly.

• Use unset() to remove specific session variables.

• Use session_destroy() to terminate the session and clear all data.

• Regenerate session IDs with session_regenerate_id() to prevent hijacking.

Check the code below for reference:

<?php
session_start();
$_SESSION[‘user’] = ‘CodingBlocks’;
echo $_SESSION[‘user’];
unset($_SESSION[‘user’]);
session_destroy();
?>

6. What is the difference between include and require?

a. Include :

• Includes and executes the specified file

• Generates a warning if the file is not found or has an error.

• The script continues to execute after warning

b. require :

• Includes and executes the specified file

• Generates a fatal error if the file is not found or has an error.

• The script stops executing immediately after the error

7. What is the use of the construct() and destruct() methods in PHP?

In PHP, the construct() and destruct() methods are special functions used in object- oriented programming to manage the lifecycle of objects. The contruct() method, also known as the constructor, is automatically called when an object is created. It is commonly used to initialize properties, set up dependencies, or perform any other setup tasks required for the object. For instance, it can accept parameters to initialize object attributes, such as setting a user’s name or connecting to a database. On the other hand, the destruct() method, or destructor, is automatically called when an object is destroyed or goes out of scope. It is primarily used for cleanup tasks, such as closing database connections, releasing resources, or performing any final operations before the object is removed from memory. Together, these methods help ensure proper initialization and cleanup of objects, making them essential for efficient resource management in PHP applications.

8. What is JIT (Just-In-Time) compilation in PHP 8?

JIT compilation in PHP 8 is a performance enhancement aimed at improving the execution speed of PHP code, particularly for non-web or CPU-intensive applications. It optimizes commonly executed code by converting it into machine code, reducing execution time. While it may not provide huge gains for typical web applications, it offers significant benefits for CLI scripts and long-running processes.

9. What do PEAR in PHP stand for and its key features and uses?

PEAR (PHP Extension and Application Repository) is a framework and distribution system for reusable PHP code components. It provides a collection of libraries, classes, and tools that developers can use to streamline their development process by reusing pre-built PHP components.

Key Features and Uses of PEAR:

• Code Reusability: PEAR allows developers to easily reuse PHP code in various projects. It offers a wide range of packages for common tasks such as database interaction, XML parsing, web services, authentication, and more.

• Package Management: PEAR has its own package manager (pear command- line tool), which allows developers to easily install, update, and manage packages. The packages can be installed from the official PEAR repository or custom repositories.

• Standardization: PEAR promotes the use of consistent coding standards. It defines coding conventions and best practices, making it easier for developers to work on projects collaboratively.

• Autoloading: PEAR supports autoloading, meaning that the necessary PHP classes and libraries are automatically loaded when needed, reducing the need for manual inclusion of files.

• Cross-Platform: PEAR packages are designed to work across different platforms, making it easier to integrate code in applications running on various operating systems.

• Quality Control: Packages in the PEAR repository are subject to review, which helps ensure that they follow good coding practices and are reliable.

10. What is the purpose of the use keyword in PHP?

The use keyword allows you to import classes, interfaces, functions, or constants from a namespace into your PHP file, so you don't have to write the full namespace path each time you reference them. It simplifies the usage of classes and functions from namespaces, making your code cleaner and more readable.

11. Explain the new match expression introduced in PHP 8.

The match expression, introduced in PHP 8, is a more powerful and concise alternative to the traditional switch statement. Unlike switch, which performs loose comparisons (==), match uses strict comparisons (===), ensuring that both the value and type must match exactly. This helps prevent unexpected behavior due to type coercion. Additionally, the match expression does not require break statements to prevent fall-through, making the code cleaner and less error-prone. It also allows for multiple values to be matched in a single case, and it returns a value directly, making it suitable for use in expressions, assignments, or return statements. The match expression is more efficient and readable, offering a modern approach to conditional logic with improved flexibility and safety.

12. What is the purpose of named arguments in PHP 8?

Named arguments, introduced in PHP 8, allow developers to pass arguments to a function or method by specifying the parameter names, rather than relying solely on their position. This feature enhances code readability and flexibility, especially when dealing with functions that have multiple parameters or optional parameters. By using named arguments, developers can pass only the arguments they need, in any order, without having to remember or rely on the correct order of parameters. This is particularly useful for functions with many parameters, making the code more self- documenting and reducing the risk of passing incorrect values. Named arguments also allow skipping optional parameters, as long as the required ones are specified first. Overall, this feature improves the clarity and maintainability of PHP code.

13. What are PHP Streams?

PHP Streams are a way to handle data from various sources (like files, network resources, or in-memory data) using a unified interface. They allow reading, writing, and manipulating data sequentially from or to different resources, such as files (file://), HTTP (http://), or custom wrappers. Streams are represented as resources and are managed using functions like fopen(), fread(), fwrite(), and fclose(). This abstraction makes it easier to interact with different data sources without dealing with their specific details, and it's especially useful for working with large amounts of data or remote resources.

14. How would you improve the performance of a PHP application?

To improve the performance of a PHP application:

• Enable OPcache: Cache compiled PHP bytecode to reduce the overhead of compiling scripts on every request.

• Use Caching: Implement caching mechanisms like Redis or Memcached to store frequently accessed data and reduce database queries.

• Optimize Database Queries: Ensure queries are efficient by using indexed columns, prepared statements, and selecting only necessary data.

15. What is the difference between public, protected, and private visibility in PHP?

In PHP, public, protected, and private are visibility modifiers that control access to class properties and methods:

• public: Properties or methods declared as public are accessible from anywhere, both inside and outside the class. There are no restrictions on their access.

• protected: Protected properties or methods are accessible within the class itself and by subclasses (child classes), but not from outside the class or its hierarchy.

• private: Private properties or methods are only accessible within the class in which they are defined and cannot be accessed by subclasses or external code.