double datetimeToNumber(const QDateTime &dt, bool is1904)
{
//Note, for number 0, Excel2007 shown as 1900-1-0, which should be 1899-12-31
QDateTime epoch(is1904 ? QDate(1904, 1, 1): QDate(1899, 12, 31), QTime(0,0));
double excel_time = epoch.msecsTo(dt) / (1000*60*60*24.0);
#if QT_VERSION >= 0x050200
if (dt.isDaylightTime()) // Add one hour if the date is Daylight
excel_time += 1.0 / 24.0;
#endif
if (!is1904 && excel_time > 59) {//31+28
//Account for Excel erroneously treating 1900 as a leap year.
excel_time += 1;
}
return excel_time;
}
