Effects: Attempts to parse the input stream
is
into the
file_time tp using
the format flags given in the NTCTS
fmt
as specified in
[time.parse]. If the parse fails to decode a valid date,
is.setstate(ios_base::failbit) is called and
tp is not modified
. If
%Z is used and successfully parsed,
that value will be assigned to
*abbrev if
abbrev is non-null
. If
%z (or a modified variant) is used and successfully parsed,
that value will be assigned to
*offset if
offset is non-null
. Additionally, the parsed offset will be subtracted from
the successfully parsed timestamp prior to assigning that difference to
tp.