ostream utilities
You may need to use these ostream methods for housekeeping:
Deliver any pending buffered output for this ostream.
opfx is a prefix method for operations on ostream
objects; it is designed to be called before any further processing. See
ostream::osfx for the converse.
opfx tests that the stream is in state good, and if so
flushes any stream tied to this one.
The result is 1 when opfx succeeds; else (if the stream state is
not good), the result is 0.
osfx is a suffix method for operations on ostream
objects; it is designed to be called at the conclusion of any processing. All
the ostream methods end by calling osfx. See
ostream::opfx for the converse.
If the unitbuf flag is set for this stream, osfx flushes
any buffered output for it.
If the stdio flag is set for this stream, osfx flushes any
output buffered for the C output streams `stdout' and `stderr'.