From Date Should Be Greater than To Date Check In asp.net

From Date Should Be Greater than To Date Check In asp.net

Step :1 Design  web from .aspx page

<div>

        <asp:ScriptManager ID="sm" runat="server">

        </asp:ScriptManager>

        From

        <asp:TextBox ID="txtFrom" runat="server" OnTextChanged="txtFrom_TextChanged" AutoPostBack="true"></asp:TextBox>

        <cc1:CalendarExtender ID="CalendarExtender2" runat="server" PopupButtonID="txtFrom"

            Enabled="True" TargetControlID="txtFrom" ClearTime="True" TodaysDateFormat="MM/dd/yyyy"

            Format="MM/dd/yyyy">

        </cc1:CalendarExtender>

        <br />

        To<asp:TextBox ID="txtto" runat="server" OnTextChanged="txtto_TextChanged" AutoPostBack="true"></asp:TextBox>

        <cc1:CalendarExtender ID="CalendarExtender1" runat="server" PopupButtonID="txtto"

            Enabled="True" TargetControlID="txtto" ClearTime="True" TodaysDateFormat="MM/dd/yyyy"

            Format="MM/dd/yyyy">

        </cc1:CalendarExtender>

       

    </div>

Step 2: Logic on .Cs apge

   protected void txtFrom_TextChanged(object sender, EventArgs e)

    {

        ChkDate();

    }

    protected void txtto_TextChanged(object sender, EventArgs e)

    {

        ChkDate();

    }

    public void ChkDate()

    {

        DateTime a = new DateTime();

        DateTime b = new DateTime();

        a = Convert.ToDateTime(txtFrom.Text);

        if (string.IsNullOrEmpty(txtto.Text))

        {

        }

        else

        {

            b = Convert.ToDateTime(txtto.Text);

            if (a < b)

            {

                ScriptManager.RegisterStartupScript(this.Page, this.Page.GetType(), "Alert", "alert('ok');", true);

            }

            else

            {

                ScriptManager.RegisterStartupScript(this.Page, this.Page.GetType(), "Alert", "alert('From Date Is greater Than To date!');", true);

            }

        }

    }

}