Solved QDateTime::toMSecsSinceEpoch() always treats my time as local. Can't get toTimeSpec() to work

[yuanqufucius]

I want milliseconds since epoch from a time string.
I understand the epoch is time since midnight 1970-Jan-01 in UTC.

With:

return QDateTime::fromString("2020-01-28 00:00:00", "yyyy-MM-dd 00:00:00").toMSecsSinceEpoch()

I get 1580191200000, which is 2020-01-28 06:00:00. This would make sense if QDateTime::fromString() defaults to my system's local time. Since I am in UTC-6 time zone.

But even if I set the timespec to UTC, as in I am telling QT that the time given "2020-01-28 00:00:00" is in UTC

return QDateTime::fromString("2020-01-28 00:00:00", "yyyy-MM-dd 00:00:00").toTimeSpec(Qt::UTC).toMSecsSinceEpoch()

I still get 1580191200000. Is it a bug or how am I doint this wrong?

Thanks!

[KroMignon]

@yuanqufucius said in QDateTime::toMSecsSinceEpoch() always treats my time as local. Can't get toTimeSpec() to work:

return QDateTime::fromString("2020-01-28 00:00:00", "yyyy-MM-dd 00:00:00").toTimeSpec(Qt::UTC).toMSecsSinceEpoch()

Hello and welcome to Qt Forum, toTimeSpec() is not the right method, you should use setTimeSpec().

return QDateTime::fromString("2020-01-28 00:00:00", "yyyy-MM-dd 00:00:00").setTimeSpec(Qt::UTC).toMSecsSinceEpoch();

QDateTime::toTimeSpec() will create a new QDateTime at same epoch time but with another time zone.
QDateTime::setTimeSpec() will change the time zone of the QDateTime instance.

[yuanqufucius]

Thanks! That would make sense.