Data Controls :: Dynamically Find Difference Of Check In And Out Time And Display In GridView Row

grid:

<asp:TemplateField HeaderText="Outdoor Hours" ItemStyle-HorizontalAlign="Right">
<ItemTemplate>
<asp:Label runat="server" ID="lblOutdoorHours" Text='<%# calculateOutdoorHours(Eval("CheckOut")) %>'></asp:Label>
</ItemTemplate>
</asp:TemplateField>

Function:

protected string calculateOutdoorHours(object CheckOut) {
for (int i = 0; i < grdAttendance.Columns.Count; i++) {
string nextCheckIn = grdAttendance.Rows[i].Columns[1].Text;
TimeSpan duration = DateTime.Parse(nextCheckIn.ToString()).Subtract(DateTime.Parse(CheckOut.ToString()));
return duration.ToString();
}
}