QTWidgets QTableWidget crash with segfault

Question

I have this signal on QPushButton:

void MainWindow::on_addNode_clicked()
{
    ui->nodesTable->insertRow(ui->nodesTable->rowCount());
    if(ui->nodesTable->rowCount()>1)
    {
        ui->nodesTable->item(ui->nodesTable->rowCount()-1, 0)->setText(ui->nodesTable->item(ui->nodesTable->rowCount()-2,0)->text());
    }
    else
    {
        ui->nodesTable->item(ui->nodesTable->rowCount()-1, 0)->setText(QString::fromStdString("0"));
    }
}

But it crashes with segmentation fault each time when I click the button. As I understood, item(...) give nullptr but why?

Answer 1

at the first time there is no item in your table, your application crashed if pointer pointed non and when you want to reach it!

try this;

void MainWindow::on_addNode_clicked()
{
    ui->nodesTable->insertRow(ui->nodesTable->rowCount());
    if( !ui->nodesTable->rowCount() )
    {
        ui->nodesTable->item(ui->nodesTable->rowCount()-1, 0)->setText(ui->nodesTable->item(ui->nodesTable->rowCount()-2,0)->text());
    }
    else
    {
        ui->nodesTable->setItem(0, 0,new QTableWidgetItem(QString("New Item")));
    }
}