/**************************************************************************
Goal:
To be able to calculate current age in several different units.

Strategy:
Obtain current datetime with datetime function.  Then either convert from
elapsed seconds to some other unit or use the intck function to find the
number of intervals.

Documentation:
"SAS Language, Reference, Version 6, First Edition", Pages 128-131, Ch. 11
"Combining and Modifying SAS Datasets, Examples", Pages 172-173
***************************************************************************/

data test;
  input eventdt datetime.;               /* date and time of event */
  curdt=datetime();                      /* current date and time  */

  seconds=curdt-eventdt;                 /* find elapsed seconds *
  age=seconds/(365.25*24*60*60);         /* convert from seconds to years */

  /* see Combining and Modifying SAS Datasets */
  exactage=int(intck('dtmonth',eventdt,curdt)/12);
  if month(datepart(eventdt))=month(datepart(curdt)) then
     exactage=exactage-(day(datepart(eventdt))>day(datepart(curdt)));


  /*
    If you need to calculate late fee for unpaid silver spoon by months, calculate
    elapsed months as follows.  Note: the intck function counts the number of times
    the time interval starts.  This works great if your billing cycle begins at the
    beginning of the month.
  */
  months=intck('dtmonth',eventdt,curdt);
cards;
10oct1972:03:45:13.2
15nov1996:00:00:00.0
01jan1960:00:00:00.0
15nov2096:00:00:00.0
;


proc print label;run;