Calculate age

[Joseph Mann]

Could someone tell me how to caluculate someones age. I can get to how old someone will be by time the year is out with "(date()-DOB)/365" : where DOB is a birthdate, but if they haven't reached there birthday yet it is inaccurate.

Thanks
Joe

[whanigsberg]

RE: Calculate age

It's been done (more than once). Search this board on "age".

Bill

[crimmelcp]

RE: Calculate age

Joseph:
Downloda this sample app.
Save to a new directory and then unip the file to that directory.
It will give you some date examples
Charlie Crimmel

[Daniel Earley]

RE: Calculate age

Change the 365 to 365.25. I would also make your answer an INT, which would make it a whole number, not a fraction.

[Brent Warwick]

RE: Calculate age

Joseph,

In Dr. Wayne's books he has a Global Function for calculating age that is accurate even for complicated situations such as leap years, etc.

Dividing by 365 or even 365.25 can have errors at times.

His example uses Alpha Five syntax, etc. and as a potential future user, I have not done this with Alpha 5, but have used the same technique with other languages/database products.

If you have the books, just make a global function as he described.

The basic idea is:

1. Subtract the YEAR of DOB from the YEAR of current date or any date at which you need the age (such as admission date for medical records). We'll call that the "target date".

2. If the MONTH of DOB is less than the MONTH of target date, then the age from step 1 is correct.

3. If the MONTH of DOB is greater than the MONTH of target date, then subtract 1 from the result of step 1.

4. If the MONTH of DOB is equal to the MONTH of target date,then if the DAY of DOB is less than or equal to the DAY of target date, the result is that from step 1, else subtract 1 from the step one result.

Hope this helps.

Brent

[Stephen Williams]

RE: Calculate age

This one is from Ira... how does this NOT work?

function Age as N(Birthday as D)
years = val(left(cdate(date()),4))-val(left(cdate(birthday),4))
if val(right(cdate(date()),4))>=val(right(cdate(birthday),4))
age = years
else
age = years - 1
end if
end function

[JerryBrightbill]

RE: Calculate age

Funny, I posted that exact function code originally a long while ago. I am glad it is getting around. I hoped others would get some use out of it. Every test I have thrown at it works, including leap years etc.

One of the great things about this forum is how code snippets and functions get passed around until no one is sure where the source was. Kinda like an open code system where many people end up using the best of everyone elses ideas.

Jerry

[csda1]

RE: Calculate age

Stephen,

I don't think I wrote that code. For one thing, if I wrote it (as opposed to suggesting some modifications to someone else's), it would look more like this;


function Age as N(Birthday as D)

Age = year(date())-year(birthday)
if val(right(cdate(birthday),4)) > val(right(cdate(date()),4))
age = age - 1
end if

end function



Try this function, which I did write.
Note that Age= is one long expression line. Make sure it is all together or you should use a line continuation.



function Age as N(Birthdate as D,CompareDate as D)

' Computes difference in years of CompareDate-Birthdate and
' returns fractional years.
' Fractional value is 0 on anniversary of date
' If Birthdate is blank, it uses current date
' If CompareDate is blank, it uses current date
' Value can return negative ages (which is to the future)

' Age({01/01/1999},{})

IF trim(cdate(CompareDate))==""
date2=DATE()
ELSE
date2=CompareDate
END IF

IF trim(cdate(BirthDate))==""
date1=DATE()
ELSE
date1=Birthdate
END IF

yeardiff=YEAR(date2)-YEAR(date1)

Age=yeardiff+IF(RIGHT(CDATE(date1),4)>RIGHT(CDATE(date2),4),(date2-ADDYEARS(date1,yeardiff-1))/365-1,(date2-ADDYEARS(date1,yeardiff))/365)

end function


Regards,

Ira J. Perlow
Computer Systems Design & Associates
[email protected]

[JerryBrightbill]

RE: Calculate age

As usual, your methods are cleaner than mine and more inclusive. Your initial line to get the uncorrected age using year() is much better than what I posted. Don't even know why I took the direction I did, that was some time ago.

I do like your expanded function which has more possibilities to compare dates, not just use the current date. Much more useful. Looks like I will have to go back and take another look at my function. One thing I do like to do is break down long expressions into individual calculations. Makes it easier for my meager brain to follow what I was thinking when I created it.

Jerry

[Geoffrey Hollander]

RE: Calculate age

Ira,

I'm still a little confused (nothing new for me)... Don't you still need to divide by 365.25 to get an accurate difference in days?

Nice function; very clean.

Best regards,

Geoff Hollander

[csda1]

RE: Calculate age

Geoffrey,

Dividing by 365.25 days is actually wrong in this case. The function determines the number of full years and then calculates the left-over days. With the left-over days, it would either be x or x+1 days left over for the partial year. Depending upon the day and month and whether it is a leap year, you may cross an extra day, but the fractional part of the year is still correct to be 365 for the divisor. 366 would be wrong most of the time and 365.25 would actually result in values less than correct most of the time. One could potentially determine if Feb 29th is in fact crossed and divide it by 366 in that case, but I believe that would not yield results that most would expect (in terms of a fractional value).

As far as I know, when the leap year case does happen, it seems like the last extra day 365/365 would yield a 1 extra year meaning that a person would be the same Integer age both on and the day before his birthday for that case.

Regards,

Ira J. Perlow
Computer Systems Design & Associates
[email protected]

[edech]

RE: Calculate age

The following works for me...(Today's date - DOB)/365.25
The divisor 365.25 takes care of leap years.

[Geoffrey Hollander]

RE: Calculate age

Ed,

That's what I'm talkin' 'bout. Ira?

Geoff Hollander

[csda1]

RE: Calculate age

Geoffrey,

As a quick approximation, (date()-birthdate)/365.25 works OK. The problem shows itself most prominantly on the anniversary of the birthdate, where 3 out of 4 years have a non-zero fractional. So for today's date (3/12/2001) let's do an example;

age=(date()-{03/12/1951})/365.25
age=({03/12/2001}-{03/12/1951})/365.25
age=18263/365.25
age=50.001369

Almost any other day of a year the fractional is OK, but most people don't like to see a fractional day on an anniversary like 50.001369 years. Of course, you can always round it, and that might fill the needs of most, by for fractional years (used in, say interest calculations for motgages), it doesn't cut it.

There is another problem to deal with if the years happens to cross a century not divisible by 400 (e.g. 1900 and 2100). These years happen to not be a leap year that throws the fractional off even more. While this doesn't happen so much in the current century, historical dates, family trees etc won't work very good.

Regards,

Ira J. Perlow
Computer Systems Design& Associates
[email protected]

[Geoffrey Hollander]

RE: Calculate age

Ira,

Thanks.

Geoff