Increment a QDateTime -- but stop it from being an endless loop

ShylerC

Team,

I used to += -- but with ... startdate.addDays -- Super Confused! How to increment until condition is met?

So in 'ol C++ regular I would do this -

while (startdate < enddate) {
startdate += days }

//Would see my startdate increment until it met condition.

Option 1.

while (startdate < enddate){
            QDateTime NewTime;
            NewTime=startdate.addDays(days);
            qDebug() << NewTime;
        }

Option 2

while (startdate < enddate){
            startdate.addDays(days);
            qDebug() << startdate;
}

in QT ... I get an endless loop... Any ideas?

jsulm

@ShylerC Signature of addDays is:

QDateTime QDateTime::addDays(qint64 ndays) const

That means it does NOT change the object on which it is called! It simply returns a NEW QDateTime object.
Change your code to:

while (startdate < enddate){
    startdate = startdate.addDays(days);
    qDebug() << startdate;
}

Christian Ehrlicher

The function addDays() does not modify the object but returns a new one. See http://doc.qt.io/qt-5/qdatetime.html#addDays

J.Hilk

hi
@ShylerC said in Increment a QDateTime -- but stop it from being an endless loop:

Team,

I used to += -- but with ... startdate.addDays -- Super Confused! How to increment until condition is met?

So in 'ol C++ regular I would do this -

while (startdate < enddate) {
startdate += days }

//Would see my startdate increment until it met condition.

Option 1.
while (startdate < enddate){
            QDateTime NewTime;
            NewTime=startdate.addDays(days);
            qDebug() << NewTime;
        }
in QT ... I get an endless loop... Any ideas?

add Days returns a new QDateTime, but you don't do anything with it in your code example therefore startdate never changes.

 while (startdate < enddate){
        startdate = startdate.addDays();
}

ShylerC

Thanks all!

Very clear and concise.
Worked like a charm.
Much appreciated!

I'll keep plugging along.

Thanks again.

aha_1980

@ShylerC: thanks for your feedback. then please mark this topic as SOLVED with the button Topic Tools.

Thanks