Protected, virtual function to extract elements from the input stream.
virtual streamsize _Xsgetn_s(
The buffer to contain the extracted characters.
The size of _Ptr.
The number of elements to extract.
The number of elements extracted.
The protected virtual member function extracts up to _Count elements from the input stream, as if by repeated calls to sbumpc, and stores them in the array beginning at _Ptr. It returns the number of elements actually extracted.