EDIT: It's not looking for a new line character, it's looking for a DC3 character.
It's what's known as a regular expression.
Basically, the two /
s merely indicate the start and end of the regex. Just ignore them for now. \x13
is an escape sequence, basically meaning that instead of trying to find x13
, PHP should try and find the character with the ASCII code of 13 (in hex). The same principle applies for the \x00
part - it's not trying to find \
and x00
, but instead the character with the ASCII value of 0. The asterisk (*
) means 'zero or more characters'. The '$' just means 'end of the line'.
So when this regular expression is put together, PHP will be searching for the entire pattern, in that order. I'm not very good at explaining this in an understandable manner, maybe someone else can clarify it. Or you might prefer to read about regular expressions on the web..