How to delete all rows from QTableWidget

Question

I am trying to delete all rows from a QTableWidget . Here is what I tried.

for ( int i = 0; i < mTestTable->rowCount(); ++i )
{
    mTestTable->removeRow(i);
}

I had two rows in my table. But this just deleted a single row. A reason could be that I did not create the the table with a fixed table size. The Qt Documentation for rowCount() says,

This property holds the number of rows in the table.

By default, for a table constructed without row and column counts, this property contains a value of 0.

So if that is the case, what is the best way to remove all rows from table?

Answer 1

Just set the row count to 0 with:

mTestTable->setRowCount(0);

it will delete the QTableWidgetItems automatically, by calling removeRows as you can see in QTableWidget internal model code:

void QTableModel::setRowCount(int rows)
{
    int rc = verticalHeaderItems.count();
    if (rows < 0 || rc == rows)
        return;
    if (rc < rows)
        insertRows(qMax(rc, 0), rows - rc);
    else
        removeRows(qMax(rows, 0), rc - rows);
}

Answer 2

I don't know QTableWidget but your code seems to have a logic flaw. You are forgetting that as you go round the loop you are decreasing the value of mTestTable->rowCount(). After you have removed one row, i will be one and mTestTable->rowCount() will also be one, so your loop stops.

I would do it like this

while (mTestTable->rowCount() > 0)
{
    mTestTable->removeRow(0);
}

Answer 3

AFAIK setRowCount(0) removes nothing. Objects are still there, but no more visible.

yourtable->model()->removeRows(0, yourtable->rowCount());

Answer 4

QTableWidget test;
test.clear();
test.setRowCount( 0);

Answer 5

The simple way to delete rows is to set the row count to zero. This uses removeRows() internally.

table->setRowCount(0);

You could also clear the content and then remove all rows.

table->clearContents();
table->model()->removeRows(0, table->rowCount());

Both snippets leave the headers untouched!

If you need to get rid of headers, too, you could switch from clearContents() to clear().

Answer 6

In order to prevent an app crash, disconnect all signals from the QTableView.

// Deselects all selected items
ui->tableWidget->clearSelection();

// Disconnect all signals from table widget ! important !
ui->tableWidget->disconnect();

// Remove all items
ui->tableWidget->clearContents();

// Set row count to 0 (remove rows)
ui->tableWidget->setRowCount(0);

Answer 7

Your code does not delete last row.

Try this one.

int totalRow = mTestTable->rowCount();
for ( int i = 0; i < totalRow ; ++i )
{
       mTestTable->removeRow(i);
}

In your code, on the first time, rowCount() have value 2 and value of the i is 0, so its delete 1st row,

But on the second time value of i incremented with 1, but rowCount() return the updated row count which is now 1, so, it does not delete the last row.

Hope now you ll be clear.

Answer 8

Removes all items not in the headers from the view. This will also remove all selections. The table dimensions stay the same.

void QTableWidget::clearContents()

Removes all items in the view. This will also remove all selections and headers.

void QTableWidget::clear()

Answer 9

Look this post : http://forum.qt.io/topic/1715/qtablewidget-how-to-delete-a-row

QList<QTableWidgetItem*> items = table.findItems(.....);
QMap<int, int> rowsMap;
for(int i = 0; i < items.count(); i++{
  rowsMap[items.at(i).row()] = -1; //garbage value
}
QList<int> rowsList = rowsMap.uniqueKeys();
qSort(rowsList);

//Now go through your table and delete rows in descending order as content would shift up and hence cannot do it in ascending order with ease.
for(int i = rowList.count() - 1; i >= 0; i--){
  table.removeRow(rowList.at(i));
}

Answer 10

You can just add empty item model (QStandardItemModel) to your QTableView (myTableView):

itemModel = new QStandardItemModel;
ui->myTableView->setModel(itemModel);