Hi annaharris,
Please use code like below..
aspx.
<asp:TextBox ID="txtDateDiff" runat="server" />
.cs
protected void Page_Load(object sender, EventArgs e)
{
DateTime startDate = new DateTime(2012, 05, 01);
DateTime endDate = new DateTime(2013, 05, 06);
txtDateDiff.Text = endDate.Subtract(startDate).TotalDays.ToString();
}
Thanks and Regards,
Rk_Hirpara.