Your quoted documentation says otherwise. It says that a 'line' include the delimiter, '\n', in the line buffer. It also says that is no delimiter is found befo

Your quoted documentation says otherwise. It says that a 'line' include the delimiter, '\n', in the line buffer. It also says that is no delimiter is found before the EOF is reached that the line buffer will not include the delimiter. That means the line buffer can clearly indicate an incomplete line by the absence of the delimiter. To be clear, EOF isn't a 'line terminator', it's the end of the data stream.