Moves count
characters backward, if possible.
If count
would move past the start or end of the buffer, moves to the start or end of the buffer.
The return value indicates whether the iterator moved onto a dereferenceable position; if the iterator didn’t move, or moved onto the
end iterator, then false is returned. If count
is 0, the function does nothing and returns
false.
this |
an iterator |
count |
number of characters to move |
whether this moved and is dereferenceable |