integer as a QTableWidgetItem ?

[tommy]

I'd like to load QTableWidget with integers and then display selected integers. It seems that QTableWidget can accept integers as shown here:

QTableWidget myTable = new QTableWidget(10, 10, this); //make a 10x10 table
 
QTableWidgetItem *newItem = new QTableWidgetItem(1); //convert from integer
myTable->setItem(0, 0, newItem); //set object

QTableWidget myTable = new QTableWidget(10, 10, this); //make a 10x10 table

QTableWidgetItem *newItem = new QTableWidgetItem(1); //convert from integer
myTable->setItem(0, 0, newItem); //set object

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But how do you visualize a selected entry from this table (entry 0,0)? The below code evidently does not work because the returned type is wrong.

int a = myTable->item(0,0);

int a = myTable->item(0,0);

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I'd have to do this

QTableWidgetItem *a = myTable->item(0,0);

QTableWidgetItem *a = myTable->item(0,0);

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But how can I get my integer out of this? This won't return integer.

[Lykurg]

int val = -1;
QTableWidgetItem *a = myTable->item(0,0);
if (a)
  val = a->text().toInt();

int val = -1;
QTableWidgetItem *a = myTable->item(0,0);
if (a)
  val = a->text().toInt();

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You may also want have a look at QTableWidgetItem::data() and setData woth UserRole...

[tommy]

This worked great thanks!

How do you empty the QTableWidget memory after you are done using the table and want to get rid of it?

[Lykurg]

QTableWidget::clear() or QTableWidget::clearContents(). Also frees the memory:

void QTableModel::clearContents()
{
    for (int i = 0; i < tableItems.count(); ++i) {
        if (tableItems.at(i)) {
            tableItems.at(i)->view = 0;
            delete tableItems.at(i); // <--
            tableItems[i] = 0;
        }
    }
    reset();
}

void QTableModel::clearContents()
{
    for (int i = 0; i < tableItems.count(); ++i) {
        if (tableItems.at(i)) {
            tableItems.at(i)->view = 0;
            delete tableItems.at(i); // <--
            tableItems[i] = 0;
        }
    }
    reset();
}

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[tommy]

Thanks again!

But can I just delete the QTableWidgetItem object? This should free the memory, too. How woud you do that?

[Lykurg]

But can I just delete the QTableWidgetItem object? This should free the memory, too. How woud you do that?

If you only want to delete a single item which is allready assigned to the table use

QTableWidget::takeItem ( int row, int column )

QTableWidget::takeItem ( int row, int column )

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but be aware that you must delete the returned item yourself!

Example:

QTableWidgetItem *a = myTable->takeItem(0,0);
if (a)
  delete a;

QTableWidgetItem *a = myTable->takeItem(0,0);
if (a)
  delete a;

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[tommy]

Hi Lykurg,

Unfortunately it didn't work. The below code for some reason always assigns 0 to val. Why doesn't it assign 3 to val?

Thanks!

QTableWidget myTable = new QTableWidget(5, 5, this);
 
   QTableWidgetItem *newItem = new QTableWidgetItem(3);
   myTable->setItem(3, 3, newItem); 
 
   QTableWidgetItem *a = myTable->item(3,3);
   int val = a->text().toInt();

QTableWidget myTable = new QTableWidget(5, 5, this);

   QTableWidgetItem *newItem = new QTableWidgetItem(3);
   myTable->setItem(3, 3, newItem); 

   QTableWidgetItem *a = myTable->item(3,3);
   int val = a->text().toInt();

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[Lykurg]

QTableWidgetItem *newItem = new QTableWidgetItem(1); //convert from integer

QTableWidgetItem *newItem = new QTableWidgetItem(1); //convert from integer

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Why doesn't it assign 3 to val?

because the above statement is wrong. You have to use:

QTableWidgetItem *newItem = new QTableWidgetItem(QString::number(1));

QTableWidgetItem *newItem = new QTableWidgetItem(QString::number(1));

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