PHP interview Questions and Answers


PHP interview Questions and Answers

  1. What is PHP? Answer: PHP stands for Hypertext Preprocessor. It is a widely used server-side scripting language primarily designed for web development. PHP code is embedded within HTML pages and executed on the server, generating dynamic content.
  2. Explain the difference between single quotes (”) and double quotes (“”) in PHP. Answer: Single quotes (”) treat everything within them as a literal string, while double quotes (“”) allow for the interpretation of variables and escape sequences within the string.
    For example:
    $name = “John”;
    echo ‘Hello, $name’; // Output: Hello, $name
    echo “Hello, $name”; // Output: Hello, John

  3. What are the main differences between GET and POST methods in PHP? Answer: GET and POST are HTTP methods used to send data to a server. The main differences are:
    • GET appends data to the URL, while POST sends data in the body of the HTTP request.
    • GET has limitations on the amount of data that can be sent, while POST can handle larger amounts.
    • GET is less secure since the data is visible in the URL, while POST data is not visible.
  4. What is the difference between echo and print in PHP? Answer: Both echo and print are used to output data in PHP. The main differences are:
    • echo can output multiple strings separated by commas, while print can only output one string.
    • echo is slightly faster, while print returns a value of 1, allowing it to be used in expressions.
  5. Explain the difference between include and require in PHP. Answer: Both include and require are used to include external PHP files. The main differences are:
    • include produces a warning and continues execution if the file is not found, while require produces a fatal error and stops execution.
    • require is generally used when the included file is crucial for the program, while include is used when the file is optional.
  6. What is the purpose of the isset() function in PHP? Answer: The isset() function checks if a variable is set and not null. It returns true if the variable exists and has a value, and false otherwise. It is commonly used to validate form input and prevent undefined variable errors.
  7. How can you prevent SQL injection in PHP? Answer: To prevent SQL injection, it is recommended to use prepared statements or parameterized queries with placeholders. This way, user input is treated as data rather than executable code, reducing the risk of SQL injection attacks.
  8. What is the use of the header() function in PHP? Answer: The header() function is used to send raw HTTP headers to the browser. It is commonly used to set response headers, such as Content-Type, redirect the page, or handle caching.
  9. What are PHP sessions and how are they different from cookies? Answer: PHP sessions are a way to store and track user data across multiple pages or requests. Sessions use a unique identifier (session ID) stored as a cookie or passed in the URL to associate data with a specific user. Cookies, on the other hand, are small files stored on the client-side, containing data sent by the server.
  10. Explain the concept of object-oriented programming (OOP) in PHP. Answer: Object-oriented programming (OOP) is a programming paradigm that organizes code around objects, which encapsulate data and behavior. In PHP, classes are used to define objects, and they can have properties (variables) and methods (functions). OOP promotes code reusability, modularity, and easier maintenance.

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