Each formatted input function begins execution by constructing an object of class
sentry
with the
noskipws
(second) argument
false. If the
sentry
object returns
true,
when converted to a value of type
bool,
the function endeavors
to obtain the requested input
. If an exception is thrown during input then
ios_base::badbit
is turned on
in
*this's
error state
. If
(exceptions()&badbit) != 0
then the exception is rethrown
. In any case, the formatted input function destroys the
sentry
object
. If no exception has been thrown, it returns
*this.