linq XML calling c# method

问题

based on this XML

 <schedule>

 <flight="A01">
-<Aircraft mdy="Thursday, September 1, 2016" Destination="Mykonos"    
  Source="Athens" ID="A320">
  <FROM>ATH</FROM>
  <TO>MYK</TO>
  <Miles>300</Miles>
  </Aircraft>
  </flight>

  </schedule>

I have the following code

  XDocument reservation = XDocument.Load("schedulemanager.xml");

        var r = (from element in XDocument.Load("schedulemanager.xml").Descendants("Aircraft")
                 let type = element.Attribute("mdy").Value
                 select type == dtArrival.Text ? MessageBox.Show("Dates are same") : type != dtArrival.Text ? MessageBox.Show("Dates not matching") : 0).FirstOrDefault();

The first query compares datepicker date that chosen by the user, with the mdy attribute "Thursday, September 1, 2016". If dates are same, a message box appears. This works fine. But when I'm trying to call a method (returns void) an error message appears "Type of conditional expression cannot be determined because there is no implicit conversion between 'void' and 'System.Windows.Forms.DialogResult' "

I want something like this

var r = (from element in    
XDocument.Load("schedulemanager.xml").Descendants("Aircraft")
                 let type = element.Attribute("mdy").Value
                 select type == dtArrival.Text ? makeReservation()

Also, how can I have multiple if statements in linq? Something like

 if select mdy==dateTimePicker && id == flightID && something==sth...then

Another question is how a variable can be cancelled/deallocated after a time limit? For instance, how reservation can be cancelled after two days from booking. I have read about timestamp but I don't know if I'm right.

Thanks in advance, any help will be highly appreciated.

来源：https://stackoverflow.com/questions/39306498/linq-xml-calling-c-sharp-method

标签

xml

linq

function

methods