[Info-vax] check date against an given age

[Mike Rechtman]

Hein RMS van den Heuvel wrote:
> On Nov 11, 11:37 am, DTL <didier.mora... at gmail.com> wrote:
> :
>> I'm needing some help to write the following in DCL:
>> if person's age >= 60 years old then...
>> knowning that birth date in file has format JJ/MM/AA
> :
>> Didier
> 
> Salut Didier! Comment ca va?
> 
> So many ways to solve this.
> Two major details to decide on first though
> - What is the cutoff YEAR for a recorded birthday to be in the 1900s
> or 2000s ?
> - Is the decision to be taken for 'today', or for a particular date
> this year?
> 
> In the solution below I just pretended all recorded dates are in the
> 1900's  allowing for folks to be more than 100 years old. If the you
> have reason to believe that no person can be more than for example 90
> years today, then you may want to subtract 100 if you find an age >
> 90.
> That will 'fix' folks born between 2000 and now.
> 
> The solution below uses TODAY as test date.
> Use  10000*f$cvtim(,,"YEAR") if any time this years is good.
> 
> If you re-arrange the segments in 19YYMMDD  format then you can just
> subtract them from the current or sample date and then divide by 10000
> than you will get an accurate number of years.
> 
> The plain subtraction does of course NOT render an accurate number of
> days.
> For example 20090101  - 20071231 is 367 days, not 18870 days but both
> turn to 1 year which is correct because only 20070101 would be 2
> years.
> 
> In an example procedure that gives:
> 
> $ slash = "/"
> $ cutoff   = 60
> $loop:
> $ READ /END=done/PROMPT="JJ/MM/AA: " SYS$COMMAND jjmmaa
> $ yy = F$ELEM(2, slash, jjmmaa)
> $ IF yy .EQS. slash THEN GOTO loop
> $
> $ yymmdd = 10000*(1900+yy) + 100*F$ELEM(1,slash,jjmmaa) + F$ELEM
> (0,slash,jjmmaa)
> $ now    = F$CVTIME(,,"DATE") - "-" - "-"
> $ target = cutoff - ('now' - 'yymmdd') / 10000 ! Sloppy math is good
> enough for this work
> $ IF target .GT. 0 THEN target = 1
> $ write sys$output f$fao ("person is !0UL!0%Cexactly!1%Cless than!
> %Emore than!%F !UL",target,cutoff)
> $ GOTO loop
> $done:
> $ EXIT
> 
> $ @tmp   ! Run on 11/11/09 :-)
> JJ/MM/AA: 11/11/49
> person is exactly 60
> JJ/MM/AA: 10/11/49
> person is exactly 60
> JJ/MM/AA: 12/11/49
> person is less than 60
> JJ/MM/AA: 12/11/48
> person is exactly 60
> JJ/MM/AA: 12/11/47
> person is more than 60
> 
> I'm sure you can take is from there!
> 
> btw... Mike, straight date subtraction as with F$DELTA_TIME is not too
> useful as if requires knowing about leap years.
> 
> Cheers,
> Hein

On V7.3-2
$
$ start = "28-Feb-2008 0:0:0"
$ end = "1-mar-2008 0:0:0"
$ dif = f$delta_time( start,end )
$ sho sym dif
   DIF = "   2 00:00:00.00"
$
... so the lexical seems to cope with leap years (perhaps not with leap seconds)

-- 
Mike R.
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