c++ - Why is not Qt label refreshed? -

this method call button click

void changelabeltext(qlabel* mylabel) {     int countnumber = 0;     for(int = 0; < 9999; i++)//outer loop     {         for(int k = 0; k < 65000; k++)//inner loop         {             countnumber++;         }         mylabel->settext(qstring::number(countnumber));     } } 

when code runs text of label set @ end of outer loop, expected set label's text every time inner loop finishes. might causing it?

your code executed in main thread , in main thread th ui update happens on events callbacks. need force repaint ui. can calling repaint() or asking aplication process events qcoreapplication::processevents(). need make after changing label.