It is said that it is Yahoo's PHP interview with answers

Yahoo!'s PHP interview questions include answers collected from the internet. They are said to be Yahoo's interview questions.
1. Which of the following will not add john to the users array?
1. $ users [] = 'John ';
2. array_add ($ users, 'John'); // wrong
3. array_push ($ users, 'John ');
4. $ users | = 'John'; // wrong
2. What's the difference between sort (), asort () and ksort? Under what circumstances wocould you use each of these?
My an: sort ()-sort asort ()-sort key values ksort ()-sort rsort ()-reverse sort arsort () -keep key values in reverse order krsort ()-sort by key in reverse order
3. What wocould the following code print to the browser? Why?
$ Num = 10;
Function multiply ()
{
$ Num = $ num * 10;
}
Multiply ();
Echo $ num;
My an: 10 because var scope4. What is the difference between a reference and a regular variable? How do you pass by reference & why wocould you want?
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 wocould you declare a class named "myclass" with no methods or properties?
10. How wocould 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 wocould you use to redirect the browser to a new page?
1. redir () 2. header () 3. location () 4. redirect ()
My an: 2
14. What function can you use to open a file for reading and writing?
1. fget (); 2. file_open (); 3. fopen (); 4. open_file (); my an: 315. 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 = '2014/1/123'; print ereg_replace ("([0-9] +)/([0-9] +)/([0-9] +) ", 2/1/3, $ date); 17. given a line of text $ string, how wocould 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.