If we want to line feed in one string, how to do?

* Normal ( not line feed ):

string $str = "This is something string, we want to line feed. how to do?";

* Line feed:

string $str = 

"This is something string, \
we want to line feed. \
how to do?";

So, when we want to line feed in one string.
We must be add "backslash"( from left top to right bottom slash "\" )
in the every end of line