\\ in a string literal means \ in the represented
string.
\\ in a regular expression means to match \ in the searched string.
Thus, \\\\ in a string literal *representation of* a regular expression
means to match \ in the searched string.
Yeah, it's ugly. Welcome... to programming! :D
So it's escaped once because it has a special meaning in php and
escaped again because it has a special meaning in regular expressions?
Are there not enough characters to go around?