A friend recently got some pre-interview questions from YAHOO for a PHP job. Following up my previous post about programmer questions I thought I would post them to give people examples of what a large corporation like YAHOO asks.

1. Which of the following will not add john to the users array?

         1. $users[] = ‘john’;
         2. array_add($users,’john’);
         3. array_push($users,‘john’);
         4. $users ||= ‘john’;
2. What’s the difference between sort(), assort() and ksort? Under what circumstances would you use each of these?

3. What would the following code print to the browser? Why?

      $num = 10;
      function multiply(){
            $num = $num * 10;
      }
      multiply();
      echo $num;
4. What is the difference between a reference and a regular variable? How do you pass by reference & why would you want to?

5. What functions can you use to add library code to the currently running script?

6. What is the difference between foo() & @foo()?

7. How do you debug a PHP application?

8. What does === do? What’s an example of something that will give true for ‘==’, but not ‘===’?

9. How would you declare a class named “myclass” with no methods or properties?

10. How would you create an object, which is an instance of “myclass”?

11. How do you access and set properties of a class from within the class?

12. What is the difference between include & include_once? include & require?

13. What function would you use to redirect the browser to a new page?

         1. redir()
         2. header()
         3. location()
         4. redirect()
14. What function can you use to open a file for reading and writing?

         1. fget();
         2. file_open();
         3. fopen();
         4. open_file();
15. What’s the difference between mysql_fetch_row() and mysql_fetch_array()?

16. What does the following code do? Explain what’s going on there.

      $date=’08/26/2003’;
      print ereg_replace(“([0-9]+)/([0-9]+)/([0-9]+)”,\\2/\\1/\\3,$date);
17. Given a line of text $string, how would you write a regular expression to strip all the HTML tags from it?

18. What’s the difference between the way PHP and Perl distinguish between arrays and hashes?

19. How can you get round the stateless nature of HTTP using PHP?

20. What does the GD library do?

21. Name a few ways to output (print) a block of HTML code in PHP?

22. Is PHP better than Perl? – Discuss.

I have no idea if there are different levels of PHP tests within YAHOO but this seems to be much easier level than something like the Zend Certification questions which require at times encyclopedic knowledge of the language