backward_chars

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.

Parameters:

this	an iterator
count	number of characters to move

Returns:

whether this moved and is dereferenceable