How to make the value of QProgressBar start from 0?

Question

In the function - loadData(), First, show the dialog with QProgressBar,and then, call setValue() for the progressbar base on the business. when the value of progressbar increase to 100%, hide the dialog and set the value to 0.

My question is: When I enter the loadData() function again, after exec the dlgo->show(), the value of progressbar isn't start from 0, but jump from 100 to 0, and then go on.

What can I do to make the value of progressbar start from 0 when I tried show the dialog again? Thank you!

void loadData() {
    mProcessBarDlg->show();

    {
      mProcessBarDlg->ui.progressBar->setValue(XX);
    }

    mProcessBarDlg->hide();
    mProcessBarDlg->ui.progressBar->setValue(0);
}

Answer 1

Set it to zero before you show it.

EDIT: The following code, derived from the poster's question, works:

#include <qapplication.h>
#include <qdialog.h>
#include <qprogressbar.h>

QDialog *mProcessBarDlg;
QProgressBar *progressBar;

void loadData() {
    mProcessBarDlg->setValue(0);
    mProcessBarDlg->show();

    for (int i = 0; i < 100000000; ++i){
        if (i % 100 == 0){
            qApp->processEvents();
        }
    }

    {
      progressBar->setValue(50);
      for (int i = 0; i < 100000000; ++i){
        if (i % 100 == 0){
            qApp->processEvents();
        }
      }
    }

    mProcessBarDlg->hide();
}


int main(int argc, char *argv[])
{
    QApplication a(argc, argv);

    mProcessBarDlg = new QDialog;
    progressBar = new QProgressBar(mProcessBarDlg);

    loadData();

    for (int i = 0; i < 100000000; ++i){
        if (i % 100 == 0){
            a.processEvents();
        }
    }

    loadData();

    QMetaObject::invokeMethod(&a, "quit", Qt::QueuedConnection);

    return a.exec();
}