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Basically I have a table widget. 2 columns in that table contain Diameters and Area repsectively.

I basically want when I enter the diameter the area get calculated in the corresponding cell. And if I enter the area, the diameter is similarly calculated.

I made the connect function that sends a signal when a cell is changed, this is used to detect the row and column to know which cell exactly and the SLOT is the function where the calculations happen. So this:

    QObject::connect(TabUI.tableWidget, &QTableWidget::itemChanged, this, &Pressurator::CalculateArea);

And this:

void Pressurator::CalculateArea(QTableWidgetItem *item)
{

//        QTableWidgetItem * item = new QTableWidgetItem;
//        double area = 0;
//        QDoubleSpinBox * diameter_SB =  static_cast<QDoubleSpinBox*>(TabUI.tableWidget->cellWidget(item->row(),0));
//        QDoubleSpinBox * area_SB =  static_cast<QDoubleSpinBox*>(TabUI.tableWidget->cellWidget(item->row(),1));

//        area = M_PI * qPow(diameter_SB->value()/2, 2);
//        area_SB->setValue(area);


    row = item->row();
    column = item->column();

    qDebug()<<"DETECTED--->"<<row<<" | "<<column;
if(column == 0){
    diameter = TabUI.tableWidget->item(row,0)->text().toDouble();
    qDebug()<<"Diameter: "<<diameter<<Qt::endl;
    area = M_PI * qPow(diameter/2, 2);
    qDebug()<<"Area: "<<area<<Qt::endl;
    TabUI.tableWidget->item(row,1)->setText(QString::number(area, 'f', 6));
}else if(column == 1){
    area = TabUI.tableWidget->item(row,1)->text().toDouble();
    diameter = qSqrt((4* area)/M_PI);
    TabUI.tableWidget->item(row,0)->setText(QString::number(diameter, 'f', 6));
}

My app keeps crashing after I enter data in one of the cells, so I don't really know how to proceed or the reason for the crash.

Mohamed El Kayal
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    what does a debugger say about the crash (error message / location)? For more info: [What is a debugger and how can it help me diagnose problems?](https://stackoverflow.com/questions/25385173) , maybe [How to debug small programs](https://ericlippert.com/2014/03/05/how-to-debug-small-programs/) – codeling Apr 25 '22 at 13:12
  • it just says that the app suddenly crashed. A friend said that every cell is null at the beginning so that I have to set an item in the cell I'm dealing with. But I'm not sur ehow to go on about that I tried using the "setItem(row, col, QTableWidgetITem)" at the beginning of the CalculateArea function but the app still crashes – Mohamed El Kayal Apr 25 '22 at 15:05

1 Answers1

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I just defined my tableWidget when constructing my form (not at the CalculateArea function) as below and it worked:

QTableWidget* tableWidget = new QTableWidget();
tableWidget->setRowCount(1);
tableWidget->setColumnCount(2);
QTableWidgetItem* item = new QTableWidgetItem("1.0");
QTableWidgetItem* item2 = new QTableWidgetItem("0.785398");
tableWidget->setItem(0, 0, item);
tableWidget->setItem(0, 1, item2);
tableWidget->show();

In QTableWidget class, the signal "itemChanged" is emitted whenever the data of item has changed. In the definition of "CalculateArea" slot, you are trying set the data which causes to emit another signal. So it will be stuck in stack overflow. You can block the signal before you are trying set the data.

row = item->row();
column = item->column();
TabUI.tableWidget->blockSignals(true);
.
. // Set your data (if / else if) ...
.
TabUI.tableWidget->blockSignals(false);
Mohammad Amin Ya'aghoubi
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