Trying to set numbers in a table but not working.

[robgeek]

Hi!

I'm trying to show numbers in a QTableWidget, but my following code is showing nothing! There is no compile error. What's going on?

for(int i = 0; i < LINES; i++)
    {
        for(int j = 0; j < COLS; j++)
        {
            QTableWidgetItem val( QString::number( 123 ) );//This number is only for test.
            ui->tableWidget->setItem(i, j, &val);
        }
    }

for(int i = 0; i < LINES; i++)
    {
        for(int j = 0; j < COLS; j++)
        {
            QTableWidgetItem val( QString::number( 123 ) );//This number is only for test.
            ui->tableWidget->setItem(i, j, &val);
        }
    }

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Thanks!

[wysota]

Create the items on heap and not on the stack.

[robgeek]

Wut?

I tried this but i get an error message:

QTableWidgetItem val( QString::number( 1 ) );
 
    for(int i = 0; i < LINES; i++)
    {
        for(int j = 0; j < COLS; j++)
        {
            val.setText( QString::number( 123 ) );
            ui->historicLM->setItem(i, j, &val);
        }
    }

QTableWidgetItem val( QString::number( 1 ) );

    for(int i = 0; i < LINES; i++)
    {
        for(int j = 0; j < COLS; j++)
        {
            val.setText( QString::number( 123 ) );
            ui->historicLM->setItem(i, j, &val);
        }
    }

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QTableWidget: cannot insert an item that is already owned by another QTableWidget

[stampede]

Wut?

http://www.cplusplus.com/reference/new/operator%20new/

[anda_skoa]

Wut?

As wysota wrote: allocate the items on the heap, not on the stack.

Your "val" instance is stack allocated. The fact that you have to use the address operator to satisfy the signature of setItem() should have been quite a strong hint already.

Cheers,
_

[robgeek]

But i used "new" and still not working!
Bellow, the entire code.

Test::Test(QWidget *parent) : QDialog( parent ), ui(new Ui::Test)
{
    ui->setupUi( this );
 
    ui->tableWidget->setColumnCount( 21 );
    QHeaderView *header = ui->tableWidget->horizontalHeader( );
    header->resizeSections(QHeaderView::Stretch);
 
    QStringList colsnames("#");
    for(int i = 0; i < COLS; i++)
        colsnames << QString::number( (i + 1) );
 
    ui->tableWidget->setHorizontalHeaderLabels( colsnames );
 
    for(int i = 0; i < LINES; i++)
    {
        for(int j = 0; j < COLS; j++)
        {
            QTableWidgetItem *val = new QTableWidgetItem( QString::number( 123 ) );
            ui->tableWidget->setItem(i, j, val);
        }
    }
 
}

Test::Test(QWidget *parent) : QDialog( parent ), ui(new Ui::Test)
{
    ui->setupUi( this );

    ui->tableWidget->setColumnCount( 21 );
    QHeaderView *header = ui->tableWidget->horizontalHeader( );
    header->resizeSections(QHeaderView::Stretch);

    QStringList colsnames("#");
    for(int i = 0; i < COLS; i++)
        colsnames << QString::number( (i + 1) );

    ui->tableWidget->setHorizontalHeaderLabels( colsnames );

    for(int i = 0; i < LINES; i++)
    {
        for(int j = 0; j < COLS; j++)
        {
            QTableWidgetItem *val = new QTableWidgetItem( QString::number( 123 ) );
            ui->tableWidget->setItem(i, j, val);
        }
    }

}

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[robgeek]

Guys! Problem fixed. All i did was add insertRow method.

for(int i = 0; i < LINES; i++)
    {
        ui->tableWidget->insertRow( i );
        for(int j = 0; j < COLS; j++)
        {
            QTableWidgetItem *val = new QTableWidgetItem( QString::number( 123 ) );
            ui->tableWidget->setItem(i, j, val);
        }
    }

for(int i = 0; i < LINES; i++)
    {
        ui->tableWidget->insertRow( i );
        for(int j = 0; j < COLS; j++)
        {
            QTableWidgetItem *val = new QTableWidgetItem( QString::number( 123 ) );
            ui->tableWidget->setItem(i, j, val);
        }
    }

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Now everything is working fine.

Thank you for your help!