Put it in a proc and run an EXEC query, same way as any other procedure.

Jeff

If the SQL function returns a string, why not use SqlCommand.ExecuteScalar method:

 using (SqlConnection conn = new SqlConnection(ConfigurationManager.ConnectionStrings["myConn"].ToString()))
            {
                conn.Open();
               
                string qstring = "SELECT dbo.fn_test('IORI')";

                SqlCommand cmd = new SqlCommand(qstring, conn);
                string s=cmd.ExecuteScalar().ToString();
                   
                Response.Write("The new string is:" + s);
            }