Question

I have an issue on Validating End Date > Start Date which is actually Date Comparision on AJAX Enabled Date Ranger !! I am wondering any inbuilt Date Range Validator is available for AJAX ASP.net

     <td align="left">
      <asp:TextBox  ID="txtFromDate" runat="server" Width="100px" style="text-align:justify" ValidationGroup="MKE" />
         <asp:ImageButton  ID="ImgBntCalc" runat="server" 
                          ImageUrl="~/AJAXImages/Calendar_scheduleHS.png" CausesValidation="False" />

    <cc1:MaskedEditExtender ID="MaskedEditExtender5" runat="server"
                            TargetControlID="txtFromDate"
                                Mask="99/99/9999"
                                MessageValidatorTip="true"
                                OnFocusCssClass="MaskedEditFocus"
                                OnInvalidCssClass="MaskedEditError"
                                MaskType="Date"
                                DisplayMoney="Left"
                                AcceptNegative="Left"
                                ErrorTooltipEnabled="True" />

        <cc1:MaskedEditValidator 
                                    ID="MaskedEditValidator5" 
                                    runat="server"
                                    ControlExtender="MaskedEditExtender5"
                                    ControlToValidate="txtFromDate"
                                    EmptyValueMessage="Date is required"
                                    InvalidValueMessage="Date is invalid"
                                    Display="Dynamic"
                                    TooltipMessage="Input a date"
                                    EmptyValueBlurredText="*"
                                    InvalidValueBlurredMessage="*"
                                    ValidationGroup="MKE" />

     <cc1:CalendarExtender  ID="CalendarExtender1" runat="server"
                            TargetControlID="txtFromDate" 
                            PopupButtonID="ImgBntCalc" />
   </td>


    <td align="left">
        <asp:Label ID="lblToDate" Text="To Date" runat="server">
        </asp:Label>
    </td>

     <td align="left">
                <asp:TextBox ID="txtToDate" runat="server" Width="100px" MaxLength="1" />
                <asp:ImageButton      ID="imgBtn2" runat="server" 
                                      ImageUrl="~/AJAXImages/Calendar_scheduleHS.png" 
                                      CausesValidation="False" />
                 <cc1:MaskedEditExtender ID="mskEditor" runat="server"
                            TargetControlID="txtToDate"
                                Mask="99/99/9999"
                                MessageValidatorTip="true"
                                OnFocusCssClass="MaskedEditFocus"
                                OnInvalidCssClass="MaskedEditError"
                                MaskType="Date"
                                DisplayMoney="Left"
                                AcceptNegative="Left"
                                ErrorTooltipEnabled="True" />

                <cc1:MaskedEditValidator 
                                    ID="mskValidator" 
                                    runat="server"
                                    ControlExtender="mskEditor"
                                    ControlToValidate="txtToDate"
                                    EmptyValueMessage="Date is required"
                                    InvalidValueMessage="Date is invalid"
                                    Display="Dynamic"
                                    TooltipMessage="Input a date"
                                    EmptyValueBlurredText="*"
                                    InvalidValueBlurredMessage="*"
                                     />
                        <cc1:CalendarExtender ID="CalendarExtender2" runat="server"
                                              TargetControlID="txtToDate" 
                                              PopupButtonID="imgBtn2" />
     </td>
</tr>

Answer 1

I Would recommend a more robust working code like below using the compareTo method

DateTime dtFrom = DateTime.Parse(txt1.Text);
DateTime dtTo = DateTime.Parse(txt2.Text);
if(dtFrom == null){//respond from date was invalid
}
if(dtTo = null){//respond to date was in valid
}
if(dtFrom.CompareTo(dtTo) >= 0){//You hit Jackpot
} 

CompareTo returns a integer value,

when < 1, dtFrom occurs earlier than dtTo

When = 0, dtFrom is equal to dtTo

When > 0, dtFrom occurs after the dtTo