Calculating Dates with Fields

Aidan asked if it is possible to calculate dates using fields. Seems he wants a date that is two weeks in the future, and thought there must be an easy way to calculate such a future date using fields. Unfortunately, there is no easy way. While Word allows you to do simple calculations using numeric values in fields, it does not allow you to perform such calculations using dates instead of numbers.

You can, however, pull dates apart into their intrinsic portions (months, days, and years), and then do your calculations, but this introduces whole new problems. All of a sudden you need to be concerned with what happens when you "roll" past the end of a month or year. The math involved in doing such a calculation is not trivial. As an example, consider the following compound field:

{QUOTE "{SET Delay "14"}{SET "DaysInMonth" {IF {DATE \@ "MM"}
<> 2 {=ROUND(30.575*{DATE \@ "MM"},0)-ROUND(30.575*{= {DATE \@
"MM"} –1},0)}{IF {=MOD({DATE \@ "yy"|, 4)} > 0 "28" "29"}}}{SET
"NextMonth" {IF {DATE \@ "MM"} = 12 "1/97" "{= {DATE \@ "MM"}
+ 1}/97}}{IF {= {REF Delay} + {DATE \@ "dd"}} <= {DaysInMonth}
{DATE \@ "MMMM {= {REF Delay} + {DATE \@ "dd"}}, yyyy"}{QUOTE
"{NextMonth \@ "MMMM"} {= {REF Delay} + {DATE \@ "dd"} –
{DaysInMonth}}, {IF {DATE \@ "MM"} <> 12 {DATE \@ "yyyy"}{DATE
\@ "{= 1 + {DATE \@ "yyyy"} \# "xxxx"}" }}}}"}

This will return the date in two weeks time (specified in the first line where the Delay value is set. The drawback, of course, is the compound nature of the field—there are over 30 different fields just within this compound field! Even this implementation, as formidable as it looks, will not handle leap years correctly in all instances. (It won't handle leap years correctly in century years divisible by 400.)

Is there an easy way to calculate future dates? Yes, there is—simply use macros. With just a couple of simple instructions you can make short work out of otherwise difficult date calculations. The way this is done was covered in an earlier WordTips; you can also find information at the following Word MVP page:

http://wordmvp.com/FAQs/MacrosVBA/DateOfPrevMonth.htm

WordTips is your source for cost-effective Microsoft Word training. (Microsoft Word is the most popular word processing software in the world.) This tip (1579) applies to Microsoft Word 97, 2000, 2002, and 2003. You can find a version of this tip for the ribbon interface of Word (Word 2007 and later) here: Calculating Dates with Fields.