Question

I want to change the Amount cell when Qty or Price changed.

Amount = Qty * Price

I tried this code and it’s always giving me ArgumentOutOfRangeException .

private void dataGridView1_CellValueChanged(object sender, DataGridViewCellEventArgs e)
        {
            if (dg_invoices_items.Columns[e.ColumnIndex].Name == "qty")
            {   
                dg_invoices_items[e.RowIndex, 4].Value =Convert.ToString(
                        Convert.ToInt32(dg_invoices_items[e.RowIndex, 2].Value) *
                        Convert.ToInt32(dg_invoices_items[e.RowIndex, 3].Value));
            }
        }

Answer 1

Column indexes start at 0, your column indexes are one too high.

• 1st column: 0, Product
• 2nd column: 1, Qty
• 3rd column: 2, Price
• 4th column: 3, Amount

To avoid this you can probably use named columns:

dg_invoices_items["Qty", e.RowIndex].Value = Convert.ToString(
     Convert.ToInt32(dg_invoices_items["Price", e.RowIndex].Value) *
     Convert.ToInt32(dg_invoices_items["Amount", e.RowIndex].Value));

Altough I cannot test any code at the moment, so this might not work.