Get year difference between two date get two date difference of several years

Class Program
{
Static Void Main ( String [] ARGs)
{
String Date = " 2011-08-15 " ;
Datetime D0 = datetime. parse (date );
Console. writeline (d0.tostring ( " D0 is: yyyy-mm " ));
Datetime d1 = datetime. now;
Console. writeline (d1.tostring ( " D1 is: yyyy-mm " ));

IntR = getdatediffyears (D0, D1 );
Console. writeline (R. tostring ());
Console. Read ();
}

///   <Summary>
/// Get difference between two date
/// Returns the time difference between two dates.
///   </Summary>
///   <Param name = "D0"> Start date </Param>
///   <Param name = "d1"> End Date </Param>
///   <Returns> </returns>
Static Int Getdatediffyears (datetime D0, datetime D1)
{
Int Y = d1.year-d0.year;
Int M = d1.month-d0.month;
Int D = d1.day-d0.day;
If (D> 0 )
M ++;
If (D < 0 )
M --;
Int R = y * 12 + M;
If (R %12 = 0 )
{
R = r/ 12 ;
}
Else
{
R = r/ 12 + 1 ;
}
Return R;
}
}