datedif in excel when the number format is [$-409]d-mmm-yyyy;@

I have two columns with the format [$-409]d-mmm-yyyy;@, I want to calculate the difference of date of these two columns. Please 开发者_如何学JAVAhelp.

Thanks

The =datedif() formula will do that for you, as per http://www.cpearson.com/excel/datedif.aspx:

=datedif(FirstDate, LaterDate, Interval)

Where FirstDate is the earlier date, LaterDate is the later date, and interval is the return type. I usually use 'm' for months, since this can be divided by 12 to get decimal years. Lots of other options, though.