c# - check if age is <18 datepicker wpf -

i'm making application user has more 18. if he/she less 18 messagebox appears saying "under age". i'm using datepickerto select users d.o.b. problem i'm not entirely sure on how code gave go looking @ tutorials tutorials seem datetimepickers.

my code follows:

xaml

<datepicker horizontalalignment="center" name="dpkdob" grid.column="1" verticalalignment="top" grid.row="1" /> 

xaml.cs

 int age = datetime.today.year - tbkdob.value.year;  if (age < 18)  {      messagebox.show("under age");  } 

i have tested in visual studio. please find below working code :

xaml :

<datepicker horizontalalignment="center" name="dpkdob" grid.column="1"     verticalalignment="top" grid.row="1"     selecteddatechanged="dpkdob_selecteddatechanged"/> 

xaml.cs :

public mainwindow() {     initializecomponent(); }  private void dpkdob_selecteddatechanged(object sender, selectionchangedeventargs e) {     var ageinyears = getdifferenceinyears(dpkdob.selecteddate.value, datetime.today);     if (ageinyears < 18)     {         messagebox.show("under age");     } }  int getdifferenceinyears(datetime startdate, datetime enddate) {     return (enddate.year - startdate.year - 1) +         (((enddate.month > startdate.month) ||         ((enddate.month == startdate.month) && (enddate.day >= startdate.day))) ? 1 : 0); }