have two calendar extendar dates

Question

I have two calendar extendars:

One

<asp:TextBox ID="txtDOB" runat="server" Text="" />
<asp:CalendarExtender ID="calDOB" runat="server" TargetControlID="txtDOB" PopupButtonID="imgCalendarDOB"  />
<img src="images/calendar_rbc.gif" class="calenderImg" id="imgDOB" alt="" style="vertical-align: middle;cursor: pointer"  />
<img src="images/clear.png" class="calenderClearImg" alt=" " tabindex="0" id="clearDOB onclick="clearInput('<%=txtDOB.ClientID %>')" onkeypress="clearInput('<%=txtDOB.ClientID %>')" style="vertical-align: middle; cursor: pointer"  />
<asp:RequiredFieldValidator runat="server" ControlToValidate="txtDOB" ErrorMessage="*" ID="rdqDate"></asp:RequiredFieldValidator>

Two

<asp:TextBox ID="txtStartDate" runat="server" Text="" style="padding-left:8px;width:136px;" />&nbsp;
<asp:CalendarExtender ID="calStartDate" runat="server" TargetControlID="txtStartDate" PopupButtonID="imgCalendarStartDate"   />
<img src="images/calendar_rbc.gif" class="calenderImg" id="imgStartDate" alt="" style="vertical-align: middle;cursor: pointer"  />
<img src="images/clear.png" class="calenderClearImg" alt=" " tabindex="0" id="clearStartDate" onclick="clearInput('<%=txtStartDate.ClientID %>')" onkeypress="clearInput('<%=txtStartDate.ClientID %>')" style="vertical-align: middle;cursor: pointer"  />
<asp:RequiredFieldValidator runat="server" ControlToValidate="txtStartDate" ErrorMessage="*" ID="RequiredFieldValidator1"></asp:RequiredFieldValidator>  

From this I need to calculate the aghe difference and then show that in years in another text box. How is this possible?

Answer 1

You can convert the textbox dates to datetime object first like below:

DateTime myDate = DateTime.ParseExact(YourTextBox.Text, "yyyy-MM-dd HH:mm:ss,fff",
                                   System.Globalization.CultureInfo.InvariantCulture)

Then you should be able to calculate timespan like below:

TimeSpan span = Date1 - Date2;

Then to convert in years.

int years = (span).Year

Or you can create function to be generic also.

public static double DifferenceTotalYears(this DateTime start, DateTime end)
{
    // Get difference in total months.
    int months = ((end.Year - start.Year) * 12) + (end.Month - start.Month);
    // substract 1 month if end month is not completed
    if (end.Day < start.Day)
    {
        months--;
    }
    double totalyears = months / 12d;
    return totalyears;
}