when i was copying this code in my project then i dint get the variable "store"

private void dataGridView1_CellValueNeeded(object sender,
    DataGridViewCellValueEventArgs e)
{
    if (store.ContainsKey(e.RowIndex))
    {
        // Use the store if the e value has been modified
        // and stored.
        e.Value = store[e.RowIndex];
    }