QTableWidget - how do I initialize items?

[frankiefrank]

This is a Newbie question so I'm in the right place to ask it.

I have a form with a QTableWidget in it, called tblMyTable.

I wrote this code to be executed when clicking on a push button:

ui.tblMyTable->setRowCount(10);
ui.tblMyTable->setColumnCount(3);
QTableWidgetItem itm(QString("blablabla"));
 
itm.setText("blabla");
ui.tblMyTable->setItem(1, 1, &itm);

ui.tblMyTable->setRowCount(10);
ui.tblMyTable->setColumnCount(3);
QTableWidgetItem itm(QString("blablabla"));
	
itm.setText("blabla");
ui.tblMyTable->setItem(1, 1, &itm);

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When running, my code creates the 10x3 table but there is no data in any of the cells.

Before I tried entering data directly using:

ui.tblMyTable->item(1, 1)->setText("boo");

ui.tblMyTable->item(1, 1)->setText("boo");

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but this resulted in a read access violation error.

[high_flyer]

You are allocating your item on the stack, and once the slot exits, the item is destroyed, leaving the the pointer in the table pointing to outer space.

ui.tblMyTable->setRowCount(10);
ui.tblMyTable->setColumnCount(3);
//QTableWidgetItem itm(QString("blablabla"));
 
itm.setText("blabla");
ui.tblMyTable->setItem(1, 1, new QTiableItem(QString("blablabla")));

ui.tblMyTable->setRowCount(10);
ui.tblMyTable->setColumnCount(3);
//QTableWidgetItem itm(QString("blablabla"));
	
itm.setText("blabla");
ui.tblMyTable->setItem(1, 1, new QTiableItem(QString("blablabla")));

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[frankiefrank]

Thanks for the reply, high_flyer, but in your code, is it possible you meant this:

ui.tblMyTable->setRowCount(10);
ui.tblMyTable->setColumnCount(3);
//QTableWidgetItem itm(QString("blablabla"));
 
//itm.setText("blabla");  // comment this line as well
// Then allocate a new object like this:
ui.tblMyTable->setItem(1, 1, new QTableWidgetItem(QString("blablabla")));

ui.tblMyTable->setRowCount(10);
ui.tblMyTable->setColumnCount(3);
//QTableWidgetItem itm(QString("blablabla"));
	
//itm.setText("blabla");  // comment this line as well
// Then allocate a new object like this:
ui.tblMyTable->setItem(1, 1, new QTableWidgetItem(QString("blablabla")));

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[high_flyer]

yes, sorry, I forgot to comment setText() out.

[frankiefrank]

Thanks, that makes sense, I didn't think about the scope.

[frankiefrank]

Sorry, still having trouble with this, and getting Read Access error, I'm thinking it's scope related but I don't really understand how I'm supposed to be doing it.

I have a table widget and I'm trying to initialize an item inside it:

void TableTry::on_btnDoWork_clicked()
{
 
int foundIdx = getOrCreateMeasurementRowIdx(ui.txtMeasurementName->text());
 
// Here is the code executed inside getOrCreateMeasurementRowIdx:
int insertAt = ui.tblMyTable->rowCount();
ui.tblMyTable->insertRow(insertAt);
ui.tblMyTable->setItem(insertAt, 0, new QTableWidgetItem(measurementName)); // Parameter is the lineEdit.text()
 
// Back in on_btnDoWork_clicked():
ui.tblMyTable->item(foundIdx,0)->setText("boooooooo"); // THIS causes error: Access violation reading location 0x00000000
}

void TableTry::on_btnDoWork_clicked()
{

int foundIdx = getOrCreateMeasurementRowIdx(ui.txtMeasurementName->text());

// Here is the code executed inside getOrCreateMeasurementRowIdx:
int insertAt = ui.tblMyTable->rowCount();
ui.tblMyTable->insertRow(insertAt);
ui.tblMyTable->setItem(insertAt, 0, new QTableWidgetItem(measurementName)); // Parameter is the lineEdit.text()

// Back in on_btnDoWork_clicked():
ui.tblMyTable->item(foundIdx,0)->setText("boooooooo"); // THIS causes error: Access violation reading location 0x00000000
}

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Is it possible I'm not supposed to be editing items I've already added? Should I always create a new item and then use setItem?

Why can't I access the item I dynamically created?

[high_flyer]

Probably the index is wrong.
I don't know what 'foundIndx' values is.
Just for testing you can try using 'insertInx', and at any rate you should add

...
Q_ASSERT(iIndex < ui.tblMyTable.rowCount());
ui.tblMyTable->item(iIndex,0)->setText("boooooooo");

...
Q_ASSERT(iIndex < ui.tblMyTable.rowCount());
ui.tblMyTable->item(iIndex,0)->setText("boooooooo");

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[frankiefrank]

OK, I see that I should have just created new items when I wanted to replace existing items, and then use setItem. That worked for me.

Thanks for the help.