15.13.3 User-Defined Stream Buffers
Stream buffers are buffers for I/O. Their interface is defined by class basic_streambuf. For the
character types char and wchar_t, the specializations streambuf and wstreambuf, respectively,
are predefined. These classes are used as base classes when implementing the communication over
special I/O channels. However, doing this requires an understanding of the stream buffer’s operation.