how to calculate gridview column total in Textbox in windows

for this after binding data, you have to loop this grid and add column

for example if your grid name is  dataGridView then

 

decimal unit_ttl= 0; 

 decimal amouttotal= 0;

decimal taxtotal = 0;
decimal totalamount = 0;
for (int i = 0; i < dataGridView.Rows.Count; i++)
{

unit_ttl= unit_ttl+ Convert.ToDecimal(dataGridView.Rows[i].Cells[4].Value); 

amouttotal= amouttotal+ Convert.ToDecimal(dataGridView.Rows[i].Cells[5].Value);
totalamount = totalamount+ Convert.ToDecimal(dataGridView.Rows[i].Cells[6].Value);
taxtotal = taxtotal + Convert.ToDecimal(dataGridView.Rows[i].Cells[7].Value);
}

TotalUnittxt.Text = unit_ttl.ToString();
amounttxt.Text = amouttotal.ToString();
TotalTaxtxt.Text = taxtotal.ToString();
totalamounttxt.Text = totalamount.ToString();