PHP Interview Questions and Answers for 7 years experience

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PHP Interview Questions and Answers (7 Years Experience)

  1. What is PHP and why is it used?

    • Answer: PHP (Hypertext Preprocessor) is a widely-used, open-source, server-side scripting language primarily used for web development. It's embedded within HTML, allowing dynamic content generation. Its popularity stems from its ease of use, large community support, vast libraries and frameworks (like Laravel, Symfony, CodeIgniter), and its compatibility with various databases.

  2. Explain the difference between `==` and `===` in PHP.

    • Answer: `==` performs loose comparison, checking only for equality of value. `===` performs strict comparison, checking for both value and type equality. For example, `1 == "1"` is true (loose), while `1 === "1"` is false (strict) because they have different types.

  3. What are superglobals in PHP? List some examples.

    • Answer: Superglobals are built-in variables in PHP that are always accessible, regardless of scope. Examples include `$_GET`, `$_POST`, `$_REQUEST`, `$_SESSION`, `$_COOKIE`, `$_SERVER`, `$_ENV`, `$_FILES`, and `$GLOBALS`.

  4. How do you handle errors in PHP?

    • Answer: PHP offers several error handling mechanisms: `try...catch` blocks for exceptions, `set_error_handler()` to customize error reporting, `error_reporting()` to control the level of error reporting, and logging errors to files or databases for later analysis. Utilizing a robust logging system is crucial for production environments.

  5. Explain the concept of namespaces in PHP.

    • Answer: Namespaces prevent naming collisions by providing a hierarchical structure for organizing code. They allow you to use the same class or function names in different parts of your application without conflicts. They are declared using the `namespace` keyword.

  6. What are the different ways to include files in PHP?

    • Answer: `include()`, `include_once()`, `require()`, and `require_once()`. `include()` and `include_once()` generate a warning if the file is not found and continue execution. `require()` and `require_once()` generate a fatal error and halt execution if the file is not found. `_once` versions prevent the file from being included more than once.

  7. What is the difference between `session_start()` and `session_destroy()`?

    • Answer: `session_start()` initializes a session, making it accessible for storing and retrieving data. `session_destroy()` destroys the current session, deleting all session data associated with it.

  8. Explain the concept of object-oriented programming (OOP) in PHP.

    • Answer: OOP is a programming paradigm that uses "objects" containing data (properties) and methods (functions) to structure code. Key concepts include encapsulation, inheritance, polymorphism, and abstraction. PHP supports OOP through classes, objects, interfaces, and abstract classes.

  9. What are different types of database interactions in PHP?

    • Answer: PHP interacts with databases using extensions like MySQLi, PDO (PHP Data Objects), and others. These extensions provide functions for connecting to a database, executing queries (SELECT, INSERT, UPDATE, DELETE), fetching data, and handling transactions. PDO is generally preferred for its database-agnostic approach.

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