Each
unformatted
output function begins execution by constructing an object of class
sentry.  If that object returns
true,
while converting to a value of type
bool,
the function endeavors
to generate the requested output
.  If an exception is thrown during output, then
ios_base::badbit
is set
in
*this's
error state
.  If
(exceptions() & badbit) != 0
then the exception is rethrown
.  In any case, the unformatted output function ends by destroying the
sentry object, then, if no exception was thrown, returning the value
specified for the unformatted output function
.