How to apply certain code when checkbox is checked in gridview using LINQ?

Question

I want to execute this blow code to only checked rows in GvProducts using Linq:

<ItemTemplate><asp:CheckBox ID="chkSel" runat="server" /></ItemTemplate>

Code:

double total = GvProducts.Rows.Cast<GridViewRow>()
.Sum(r => double.Parse(((TextBox)r.FindControl("txtQuantity")).Text) * double.Parse(((TextBox)r.FindControl("txtUnitprice")).Text));

Answer 1

I think we need more information to give a proper answer, to me it sound like this:

Checkbox oRb2 = (Checkbox )r.FindControl("rb_grid");double total = 0;
foreach (DataGridItem oItem in grid.Items)
{    
    if (oRb2.Checked == true)
    {
        total += GvProducts.Rows.Cast<GridViewRow>().Sum(r => double.Parse(((TextBox)r.FindControl("txtQuantity")).Text) * double.Parse(((TextBox)r.FindControl("txtUnitprice")).Text));
    }
}