uint QDateTime::toTime_t () const
Returns the datetime as the number of seconds that have passed since 1970-01-01T00:00:00, Coordinated Universal Time (Qt::UTC).
On systems that do not support time zones, this function will behave as if local time were Qt::UTC.
Note: This function returns a 32-bit unsigned integer, so it does not support dates before 1970, but it does support dates after 2038-01-19T03:14:06, which may not be valid time_t values. Be careful when passing those time_t values to system functions, which could interpret them as negative dates.
If the date is outside the range 1970-01-01T00:00:00 to 2106-02-07T06:28:14, this function returns -1 cast to an unsigned integer (i.e., 0xFFFFFFFF).