How to pass the id value for selected row in grid view asp.

Question

 

if user click the report button, it will go another page.  i have to pass this id no to that another page .so please give any suggestion

foreach (GridViewRow gr in GridView1.Rows)

{

string id = GridView1.SelectedRow.Cells[0].Text;

response.redirect("xxx.aspx?id"=+id)

}

if i used this code then i am getting first row id no only..

please give any solution for this