std::basic_filebuf<CharT,Traits>::uflow (3) - Linux Manuals
virtual int_type uflow()
Behaves like the underflow(), except that if underflow() succeeds (does not return Traits::eof()), then advances the next pointer for the get area. In other words, consumes one of the characters obtained by underflow().
The value of the character that was read and consumed in case of success, or Traits::eof() in case of failure.
This section is incomplete
Reason: no example
uflow reads characters from the associated input sequence to the get area and advances the next pointer
underflow reads from the associated file
overflow writes characters to the associated file from the put area