What is the easiest way to get the difference in months between two dates in C#?

Question

What is the easiest way to get the difference in months between two dates in C#?

ie: (date1 - date2).TotalMonths .. kind of thing. thanks!

Answer 1

The best I can suggest is to get the total number of days, and then roughly compute the number of months by dividing accordingly. Something like:

DateTime dt1 = new DateTime( 2010, 10, 23);
DateTime dt2 = new DateTime( 2010, 7, 23);
TimeSpan ts = dt1 - dt2;
int days_per_month = 30;
Console.Write( ts.TotalDays / days_per_month);

If you really are okay with something like 2010 Feb 1 - 2010 Jan 31 returning 1 month as its answer, then given the above code, you would be able to get at this easily by using

Console.Write( dt1.Month - dt2.Month);

This doesn't take into consideration the year, so I defer to the other answer here that does this. :)

Answer 2

TimeSpan Class :)

 TimeSpan span = endTime.Subtract ( startTime );
 Console.WriteLine( "Time Difference (months): " + span.Days / 30 );

Answer 3

If you don't know how to calculate date span in .net here is good example:

DateTime startTime = DateTime.Now;
DateTime endTime = DateTime.Now.AddSeconds(75);

TimeSpan span = endTime.Subtract ( startTime );
Console.WriteLine( "Time Difference (seconds): " + span.Seconds );
Console.WriteLine( "Time Difference (minutes): " + span.Minutes );
Console.WriteLine( "Time Difference (hours): " + span.Hours );
Console.WriteLine( "Time Difference (days): " + span.Days );

Source: here.

DateTime don't expose the difference in month since every month have a different number of days. The simplest way to get the month is totaldays / 30.

Answer 4

Since you already know that your dates will be the first of the month:

int totalMonths = (date2.Year - date1.Year)*12 + date2.Month - date1.Month;

Answer 5

Given the updates you have made to your original question: How about writing up a function that takes two dates and does the following,

DateTime d1 = new DateTime(2008, 12, 1);
DateTime d2 = new DateTime(2009, 1, 1);

var month_diff = (d2.Year - d1.Year)*12 + (d2.Month - d1.Month);
Console.WriteLine(month_diff);