[egenix-users] Apparent bug in RelativeDateDiff() routine

[Bob Gibson]

  Am I missing something?  It seems that the RelativeDateDiff() routine
ignores the actual number of days in the current month when calculating the
difference.  It seems to use a fixed number of days (30) for each month.
Here is a script that supports this theory.

----------------------------------------------------------------------
from mx.DateTime import *

#         Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov
actual = [ 30, 28, 30, 29, 30, 29, 30, 30, 29, 30, 29 ]

stop   = Date( 2000, 12, 1 )
finish = stop.strftime( '%m/%d/%Y' )
for mon in range( 11, 0, -1 ) :
  start = Date( 2000, mon, 2 )
  begin = start.strftime( '%m/%d/%Y' )
  delta = RelativeDateDiff( stop, start )
  correct = actual.pop()
  print "%s - %s = %2d months, and %d days [%d]" % ( finish, begin,
delta.months, delta.days, correct )
----------------------------------------------------------------------

  The output of this script is as follows:
----------------------------------------------------------------------
12/01/2000 - 11/02/2000 =  0 months, and 29 days [29]
12/01/2000 - 10/02/2000 =  1 months, and 29 days [30]
12/01/2000 - 09/02/2000 =  2 months, and 29 days [29]
12/01/2000 - 08/02/2000 =  3 months, and 29 days [30]
12/01/2000 - 07/02/2000 =  4 months, and 29 days [30]
12/01/2000 - 06/02/2000 =  5 months, and 29 days [29]
12/01/2000 - 05/02/2000 =  6 months, and 29 days [30]
12/01/2000 - 04/02/2000 =  7 months, and 29 days [29]
12/01/2000 - 03/02/2000 =  8 months, and 29 days [30]
12/01/2000 - 02/02/2000 =  9 months, and 29 days [28]
12/01/2000 - 01/02/2000 = 10 months, and 29 days [30]
----------------------------------------------------------------------

  The value in brackets '[]' is the correct number of days that should be
returned by RelativeDateDiff(), based upon the actual number of days in the
specified month.

  For example, since 2000 was a leap year, there were 29 days in Feb, 2000.
So the number of days from Feb 2, 2000 until the 1st of Mar, should be
calculated as follows:

  29 - 2 + 1 = 28

  (# of days in current month) - (current day of current month ) + (# of
days into target day in next month)

Thanks
Bob

Ps 37:16  It is better to be godly and have little than to be evil and
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