virtual iter_type do_get_time(iter_type first, iter_type last,
ios_base& x, ios_base::iostate& st, tm *pt) const;The virtual protected member function endeavors to match sequential elements beginning at first in the sequence
[first, last) until it has recognized a complete, nonempty time input field. If successful, it converts this field to its
equivalent value as the components tm::tm_hour, tm::tm_min, and tm::tm_sec, and stores the results in
pt->tm_hour, pt->tm_min, and pt->tm_sec, respectively. It returns an iterator designating the first element beyond
the time input field. Otherwise, the function sets ios_base::failbit in st. It returns an iterator designating the first
element beyond any prefix of a valid time input field. In either case, if the return value equals last, the function sets
ios_base::eofbit in st.
In this implementation, the time input field has the form HH:MM:SS, where:
HH is a sequence of decimal digits whose corresponding numeric value must be in the range [0, 24), giving the
hour of the day.MM is a sequence of decimal digits whose corresponding numeric value must be in the range [0, 60), giving the
minutes past the hour.SS is a sequence of decimal digits whose corresponding numeric value must be in the range [0, 60), giving the
seconds past the minute.