c# - Date / time control asp.net -

i have webform app calculates time difference between 2 dates , give in format number of days, total hours, total mins.

my markup code following:

<asp:label id="label20" runat="server" cssclass="label">resolved date</asp:label> <asp:textbox id="textbox14" runat="server" cssclass="textbox"      textmode="date" ontextchanged="textbox14_textchanged"></asp:textbox> 

now ontextchanged event calculate time difference date time textbox.

i have done this:.

protected void textbox14_textchanged(object sender, eventargs e) {     // date first text box      datetime dold = convert.todatetime(textbox1.text);     datetime dnew = convert.todatetime(textbox14.text);     timespan daydif = (dnew - dold);     double dayd = daydif.totaldays;     label27.text = dayd.tostring(); } 

my problem whenever there no output it? label27 not have diff of days values.

is there other event trigger not aware of?

thanks help.

i agree jon skeet use calendar controls purpose, run input validation problems text field, calendar working date object. first can add calendar fields page.

<!-- old date --> <asp:calendar id="calendar1" runat="server"></asp:calendar> <!-- new date --> <asp:calendar id="calendar2" onselectionchanged="textbox14_textchanged" runat="server"></asp:calendar> 

then in onchanged method can calculate timespan in 1 line, no sense in creating object double hold total days when can access so. unless going use many places perhaps create holder double.

protected void textbox14_textchanged(object sender, eventargs e)     {         //might add quick validation make sure date selected in both calendars.         // not sure if subtracting old new or new old can sorta out         label20.text = ((timespan)(calendar2.selecteddate - calendar1.selecteddate)).totaldays.tostring();     } 

keep in mind when onselection changed called page being refreshed cause data has submitted page in order server side processing happen. web page events not work winforms.