You can use these methods to synchronize related streams with one another:
ostream* ios::tie () const Method
Report on what output stream, if any, is to be flushed before accessing this one. A pointer value of 0 means no stream is tied.
ostream* ios::tie (ostream* assoc) Method
Declare that output stream, assoc, must be flushed before accessing this stream.
int ios::sync_with_stdio ([int switch]) Method
Unless iostreams and C stdio are designed to work together, you may have to choose between efficient C++ streams output and output which is compatible with C stdio. Use ‘ios::sync_with_stdio()’ to select C compatibility. The argument, switch, is a GNU extension; since the default value for switch is usually 1, use 0 as the argument to choose output that is not necessarily compatible with C stdio.
If you install the stdio implementation that comes with GNU 157 libio, there are compatible input/output facilities for both C and C++. In that situation, this method is unnecessary—but you may still want to write programs that call it, for portability.