Qt：将数据从 QString 转换为 Double 时出现段错误

这里有张桌子：

    ui->tableWidget->setColumnCount(4);
    for (int i = 0; i < db.gList->Goods->size(); i++)
    {
        ui->tableWidget->insertRow(i);
        ui->tableWidget->setItem(i, 0 , new QTableWidgetItem(QString::number(i)));
        ui->tableWidget->setItem(i, 1 , new QTableWidgetItem(QString::number(db.gList->Goods->at(i).GID))); //i, db.gList->Goods->at(i).gName, db.gList->Goods->at(i).gAmount, db.gList->Goods->at(i).gPrice
        ui->tableWidget->setItem(i, 2 , new QTableWidgetItem(db.gList->Goods->at(i).gName));
        ui->tableWidget->setItem(i, 3 , new QTableWidgetItem(QString::number(db.gList->Goods->at(i).gAmount)));
        ui->tableWidget->setItem(i, 4 , new QTableWidgetItem(QString::number(db.gList->Goods->at(i).gPrice)));
    }

表格中有点击表格的处理

    void MainWindow::on_tableWidget_itemClicked(QTableWidgetItem *item)
    {
        QString strText;
        int row = item->row();

        for (int i = 0 ; i < ui->tableWidget->columnCount(); i++)
        {
            strText += ui->tableWidget->item(row, i)->text() + " ";
        }
        int _gsid;
        int _gAmount;
        double _gPrice;
        _gsid = ui->tableWidget->item(row, 1)->text().toInt();
        _gAmount = ui->tableWidget->item(row, 3)->text().toInt();
        _gPrice = ui->tableWidget->item(row, 4)->text().toDouble();

        db.bList->AddItem(_gsid, _gAmount, _gPrice);

      //  ui->listWidget_2->addItem(ui->tableWidget->item(row, 2)->text());
        //qDebug() << strText;
    }

调用时

_gPrice = ui->tableWidget->item(row, 4)->text().toDouble();

发生段错误。

我究竟做错了什么？如何解决？该过程的机制是什么？