The stdiostream class makes I/O calls (through the stdiobuf class) to the standard I/O system, which does its own internal buffering. Calls to the functions declared in STDIO.H, such as printf, can be mixed with stdiostream I/O calls.
This class is included for compatibility with earlier stream libraries. You can avoid use of the stdiostream class if you use the ostream or istream class with an associated filebuf class. You must also use the stream class's ios::flags member function to set the ios::stdio format flag value.
The use of the stdiobuf class may reduce efficiency because it imposes an extra level of buffering. Do not use this feature unless you need to mix iostream library calls with standard I/O calls for the same file.
#include <stdiostr.h>
stdiobuf, ios::flags