Qtableview column get increasing

hello every one i have i have drag and dropped a tableview and write following code the code

Code:

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QStandardItemModel *listmodel = new  QStandardItemModel(this);
    QStandardItem * root = listmodel->invisibleRootItem()
    QList<QStandardItem *> row;   
for(int i =0;i<5 ;i++)
{    
row << new QStandardItem("col1") << new QStandardItem("col2") << new QStandardItem("col3") ;
    root->appendRow(row);
 
}
 
   ui->tableView->setModel(listmodel);

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but the problem is that my column get increaed ist they are 3 then 6 then 9 i want column to be 3 what should i do kindly help me

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Added after 27 minutes:

it worked i just added root->clear() :)