PHP Language Features Interview Questions

Questions to ask a PHP Developer

PHP engineers are often required to have a knowledge of the full web stack: starting with the ability to write optimized SQL queries, and wrapping up with a good understanding of HTML/CSS. When interviewing a PHP developer, make sure that you think through your requirements and ask good questions for all of them.

Here's a suggestion for a good menu of PHP interview questions:

  1. Start off with some basic SQL such as SQL Skills: Joins, Averages and Sums
  2. Include at least one simple coding task such as Separate a list of integers or Find the missing number
  3. Explore their ability to come up with an overall system design and data model with a flexible question like Design a restaurant reservation system or Design a card game system
  4. Ensure that they have a solid understanding of the basic building blocks of the web by asking about HTTP GET and POST or What are HTTP cookies?
  5. Wrap up with some CSS questions like Explore the HTML display and position attributes or CSS rule-set basics

Define the following object oriented concepts:

  • Class, object (and the difference between the two)
  • Instantiation
  • Method (as opposed to, say, a C function)
  • Static methods and classes
  • Destructor/finalizer
  • Inheritance
  • Encapsulation
  • Multiple inheritance (and give an example)
  • Abstract class
  • Interface/protocol (and different from abstract class)
  • Method overriding
  • Method overloading (and difference from overriding)
  • Polymorphism (without resorting to examples)
  • Method visibility (e.g. public/private/other)