= PHP Interview Questions =

//Also see the [[mysql-questions#phpmysql-questions|PHP/MySQL Questions]] and [[computer-science-questions|General CS Questions]].//

 * What are some of the big differences between PHP4 and PHP5?
 * What is PEAR?
 * Is PHP a typed language? Why or why not?
 * Does PHP pass data by value or reference? What's the difference?
 * Outline the process for connecting to a MySQL database, walking through connecting, querying data, and getting the return value. What are some of the things that you need to watch out for?
 * Have you ever done any unit testing in PHP with ''php-unit'' or another package? Tell me about how it went, and some of the pros & cons.
 * Have you used any PHP frameworks (Zend, PEAR, etc.)? Thoughts?
 * What's a ''GET'' request and a ''POST'' request? What are the high-level differences between each?
 * What do you have to do to be able to begin a PHP file with a short tag (e.g. ''<?'' instead of ''<?php'')?
 * What's the difference between ''ereg_match()'' and ''preg_match()''?
 * When do you want to use double quotes ('' $str = "foo" '') vs single quotes ('' $str = 'foo' '') to initialize strings? What is the difference?
 * What are ''urlencode()'' and ''urldecode()'', and why do you need them? What about ''rawurlencode()'' and ''rawurldecode()''? What's the difference?
 * Can you describe what happens, from a technical level, when a web browser brings up a web page? (e.g. there's a DNS lookup, then an HTTP request to the remote web server, then...)

== OO PHP ==

 * What's the difference between ''public'', ''private'' and ''protected''?
 * What's the difference between ''$this->myFunction()'' and ''self::myFunction()'' ?
 * When is ''_destruct()'' called?
 * How do you catch an exception? Explain exactly how a ''try-catch'' block works.
 * What does the keyword ''final'' mean?
 * How do you make an abstract class in PHP? What does that do?
 * Talk about the difference between abstract classes and interfaces in PHP. In particular, discuss the fact that an interface only specifies a 'contract' of functions you have to implement, and can't specify implementation details at all, but a class an implement more than one interface. An abstract class also specifies a contract, and //does// allow you to specify implementation in the class, but PHP doesn't let you extend more than one class at once.
 * Have you used any of the magic methods?
   * What do the ''_sleep()'' and ''_wakeup()'' functions do? (Hint: in reference to ''serialize()'' and ''unserialize()'')
   * How about ''_get()'' and ''_set()''? What are some (dis)advantages to using ''_get()'' & ''_set()'' over conventional getter and setter functions?