Get number of characters available in the sequence.
  This member is called when the number of characters available in the streambuf-derived object input sequence needs to be known. It is called by in_avail if that function can not determine its result by subtracting gptr from egptr.
  Its default behavior is to return always zero.
  This is a virtual member function that can be redefined for a specific behavior in derived classes.

Parameters.

none

 

Return Value.
  The number of characters remaining to be read in the object.

Basic template member declaration ( basic_streambuf<charT,traits> ):

int showmanyc ( );

See also.
  in_avail
  streambuf class