about gridview inside textbox

Question

Hello Sir,

 

I want assign  1 when one data add in gridview.in quantity text will show 1.

please sir give me the solution .

 

 

protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)
/{
  if (e.Row.RowType == DataControlRowType.DataRow)
  {
TextBox t = (TextBox)e.Row.FindControl("txtqunty");
t.Text = Convert.ToInt32(1).ToString();} 

 

i used this code but got error like reference object not set.

here  i am atteach a file sir please check it.

In this red place i want 1 when add 1st value.