Infinite loop upon trying to modify item in the QTableWidget

[ChrisW67]

The code presented will not compile. Changed_t is a QString (line 2) that is neither a pointer type nor has a row() or column() function (lines 5/6).

Aside from that, the assumption at line 2 that the item that changed must be the currentItem() is flawed. The item that changed is passed directly into the slot function... use that pointer.

[newtoQ_s]

Hi,

Thanks for the responses. I did some debugging and have been able to avoid the infinite loop however, I have run into the below mentioned issues.
\ I have found that there is a signal called cellchanged() that emits changes made onto the table to a custom slot called OnEditView().

This function looks for the changed item using the code above.

The issue is that I do not want this signal to be emitted upon adding new rows to the tableWidget. If I delete a row and add a new one, I do not get the following error; it occurs only upon trying to add a new row to the table.
Exception at 0x657aa87c, code:0xc0000005:read access violation at:0x0, flags=0x0 (first chance)

However, this signal is meant to be emitted only when an existing item is modified, but it seems to be emitted upon trying to add a new row as well. That is where the problem is.
I used a similar signal called itemchanged() then too I face the same issue.
But the same signal when used with QTAbleView seems to work fine.

The following is EditView

void MainWindow::onEditView()
{//Capturing the changed value from the table
    QString changed_t=ui->tableWidget->currentItem()->text();
    qDebug()<<changed_t<<__FUNCTION__;
 
   //Obtaining the row and column values for the edited item
    int r_id=ui->tableWidget->currentItem()->row();
    int c_id=ui->tableWidget->currentItem()->column();
    int line_count=0;
 
    //Changing the particular value in the file
    QFile file_r("address1.txt");
    if(!file_r.exists()){
    return;
    }
 
    QString line_app;
    QTextStream wstream(&file_r);
 
    if(file_r.open(QIODevice::ReadWrite)){
        while(!file_r.atEnd()){
        QStringList line_data;
        QString line=file_r.readLine();
        line=line.simplified();
        line_data=line.split(";",QString::SkipEmptyParts);
 
            for(int j=0;j<line_data.size();j++){
                if((j==c_id)&&(line_count==r_id)){
                    line_data.replace(j,changed_t);
                    //qDebug()<<"split: "<<line_data;
                    line.clear();
                    if(j==line_data.size()-1){
                        line_app.append(line_data.at(j)+"\n");
                    }
                    else{
                        line_app.append(line_data.at(j)+";");
                    }
                }
                else{
                    if(j==line_data.size()-1){
                        line_app.append(line_data.at(j)+"\n");
                    }
                    else{
                        line_app.append(line_data.at(j)+";");
                    }
                }
            }
           //qDebug()<<line;
           line_count++;
        }
    file_r.resize(0);
    wstream<<line_app;
    file_r.close();
}
 
}

void MainWindow::onEditView()
{//Capturing the changed value from the table
    QString changed_t=ui->tableWidget->currentItem()->text();
    qDebug()<<changed_t<<__FUNCTION__;

   //Obtaining the row and column values for the edited item
    int r_id=ui->tableWidget->currentItem()->row();
    int c_id=ui->tableWidget->currentItem()->column();
    int line_count=0;

    //Changing the particular value in the file
    QFile file_r("address1.txt");
    if(!file_r.exists()){
    return;
    }

    QString line_app;
    QTextStream wstream(&file_r);

    if(file_r.open(QIODevice::ReadWrite)){
        while(!file_r.atEnd()){
        QStringList line_data;
        QString line=file_r.readLine();
        line=line.simplified();
        line_data=line.split(";",QString::SkipEmptyParts);

            for(int j=0;j<line_data.size();j++){
                if((j==c_id)&&(line_count==r_id)){
                    line_data.replace(j,changed_t);
                    //qDebug()<<"split: "<<line_data;
                    line.clear();
                    if(j==line_data.size()-1){
                        line_app.append(line_data.at(j)+"\n");
                    }
                    else{
                        line_app.append(line_data.at(j)+";");
                    }
                }
                else{
                    if(j==line_data.size()-1){
                        line_app.append(line_data.at(j)+"\n");
                    }
                    else{
                        line_app.append(line_data.at(j)+";");
                    }
                }
            }
           //qDebug()<<line;
           line_count++;
        }
    file_r.resize(0);
    wstream<<line_app;
    file_r.close();
}

}

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Any advice please

[anda_skoa]

The error suggests that you are trying to access a null pointer.
From a quick glance it seems you are not checking the return value of QTableWidget::currentItem() before accessing it.

Cheers,
_