5.7 Using buffered streams

5.7.1 Overview

A buffered stream maintains some sort of buffer. All buffered streams use the sealed class <buffer> for their buffers. You can suggest a buffer size when creating buffered streams, but normally you do not need to do so, because a buffer size that is appropriate for the stream's source or destination is chosen for you.

Instances of the class <buffer> also contain some state information. This state information includes an index where reading or writing should begin, and an index that is the end of input to be read, or the end of space available for writing.

Buffered streams also maintain a held state, indicating whether the application has taken the buffer for a stream and has not released it yet. When a thread already holds the buffer for a stream, it is an error to get the buffer again (or any other buffer for the same stream).