
Little question
What's the output of this PHP file ?

If you answer "hello world" : congrats, you know how to read PHP !
But if you answer "?���" : actually, you are right !
Proof :
(same effect via command line)
Why ?
First clue : the entry title
Second clue by showing the invisible characters :

Third clue by doing an hex dump :

"0" characters are present and it seems PHP doesn't really like these characters...
It looks funny at first, but, when not knowing about it, debugging a project with a file containing "0" characters is pretty painful...
FIY, this file hasn't the same effect depending on the configuration... I had this strange behavior on my laptop. On my server, I had several "PHP Warning: Unexpected character in input: ' in hello.php on line 2" messages, much nicer...