Programatically loop through a DatagridView and check checkboxes

Question

I have DataGridView bound by a datatable i have checkboxes to the same.

I want to navigate or loop through the the datagridview and check mark these checkboxes ,Below is the syntax i use .

foreach(DataGridViewRow dr in dgvColumns.Rows)
{
    DataGridViewCheckBoxCell checkCell =
        (DataGridViewCheckBoxCell)dr.Cells["CheckBoxes"];
    checkCell.Value=1;
    //Also tried checkCell.Selected=true;
    //Nothing seems to have worked.!
}

Answer 1

The following worked for me, it checked the checkboxes perfectly :)

foreach (DataGridViewRow row in dgvDataGridView.Rows)
{
    ((DataGridViewCheckBoxCell)row.Cells[0]).Value = true;
}