Leap Year Test

[StephenG1CMZ]

Although years are often considered integer, sometimes it is useful in astronomy to use a real value. Both of the above suggestions fail with 1984.2 (representing 2/10 of the way through 1984) and 1984.1122 (in YYYY.MMDD format).

To avoid this I'd take the integer part of a year.
This works for YYYY, YYYY.decimal and YY.MMDD.

Code:



 EXPORT IsLeapYear(Year)
 BEGIN
  LOCAL YY:=IP(Year);

  IF FP(YY/4) ≠ 0 OR (FP(YY/100) == 0 AND FP(YY/400) ≠ 0)
  THEN 
   RETURN 0;
  ELSE
   RETURN 1;
  END;
 END;

And can be simplified to:

Code:


 

 EXPORT IsLeapYear(Year)
 BEGIN
  LOCAL YY:=IP(Year);
  RETURN NOT(FP(YY/4) ≠ 0 OR (FP(YY/100) == 0 AND FP(YY/400) ≠ 0));
 END;

I've also avoided DDAYS, which is more complicated (to calculate days it must evaluate a calendar), and might not work with years in real format rather than Prime format.