PHP Interview Questions #

PHP stands for PHP: Hypertext Preprocessor is a widely used open-source server-side scripting language especially suited for creating dynamic websites and mobile APIs.

PHP supports many databases like MySQL, Solid, PostgreSQL, Oracle, Sybase, generic ODBC, etc. PHP code is embedded within HTML.

It is used to manage dynamic content, session tracking, databases, and also to build an entire e-commerce site. By default, most of the web hosting servers support PHP and thus it contributes to cost-effectiveness.

Absolutely, here are some PHP interview questions in Markdown format:

1. What is PHP? #

PHP (Hypertext Preprocessor) is a server-side scripting language designed for web development. It’s embedded within HTML code and executed on the server, generating dynamic web content.

2. Explain the difference between echo and print in PHP. #

• echo: A language construct used to output one or more strings. It has no return value and can output multiple values separated by commas.

• print: A function that outputs a single string. It returns 1 upon success and 0 on failure. It’s slower than echo and is used less frequently.

3. What are PHP data types? #

PHP supports various data types, including:

• Integers (int)
• Floating-point numbers (float)
• Strings (string)
• Booleans (bool)
• Arrays
• Objects
• Resources
• Null

4. How can you prevent SQL injection in PHP? #

To prevent SQL injection, use prepared statements and parameterized queries. These mechanisms separate SQL code from user input, making it nearly impossible for malicious inputs to alter the SQL query.

5. Explain the concept of sessions in PHP. #

Sessions in PHP allow you to store user-specific data on the server between requests. A session is initiated using the session_start() function, and data can be stored and retrieved using the $_SESSION superglobal array.

6. What is the purpose of the $_GET and $_POST superglobal arrays? #

• $_GET: Used to collect data sent via URL query parameters (usually through the URL). Data is visible in the URL and has length limitations.

• $_POST: Used to collect data sent via HTTP POST method (usually through forms). Data is not visible in the URL and has no length limitations.

7. Explain the difference between include and require in PHP. #

• include: If the file is not found, a warning is issued, and the script continues to execute.

• require: If the file is not found, a fatal error is issued, and the script execution halts.

8. How do you handle file uploads in PHP? #

File uploads in PHP are handled using the $_FILES superglobal array. The enctype attribute of the HTML form should be set to multipart/form-data. Uploaded files are temporarily stored in a temporary directory and can be moved to the desired location using functions like move_uploaded_file().

9. What is the purpose of $_COOKIE in PHP? #

$_COOKIE is a superglobal array used to retrieve values from cookies sent by the client’s browser. Cookies are small pieces of data stored on the client’s machine and can be used to maintain state between different requests.

10. Explain the concept of autoloading in PHP. #

Autoloading is the process of automatically including class files when they are first used. It helps reduce the need for manually including numerous class files. Autoloading can be achieved using the spl_autoload_register() function or through Composer’s autoloading capabilities.

11. What is a namespace in PHP? #

A namespace is a way to encapsulate items like classes, functions, and constants to avoid naming conflicts. Namespaces provide a hierarchical way to organize code and make it more manageable.

12. How do you handle exceptions in PHP? #

Exceptions in PHP are handled using the try, catch, and optionally finally blocks. Code that might throw an exception is placed within the try block, and exceptions are caught and handled in the catch block. The finally block is executed regardless of whether an exception was thrown.

13. Explain the difference between == and === operators in PHP. #

• ==: Compares two values for equality, converting types if necessary (type coercion).
• ===: Compares two values for equality and ensures they have the same value and the same data type (strict comparison).

14. What is the purpose of the header() function in PHP? #

The header() function is used to send HTTP headers from the server to the client’s browser. It’s commonly used for tasks like setting cookies, redirecting users, and specifying content types.

15. Explain the usage of the ternary operator in PHP. #

The ternary operator (? :) is a shorthand way to write simple if-else statements. It has the format condition ? value_if_true : value_if_false. It evaluates the condition and returns one of the two values based on the result.