On 2015-03-04 07:28 AM, Steffen Nurpmeso wrote:
"Tom Van Baak" <t...@leapsecond.com> wrote:
|http://gpsworld.com/beidou-numbering-presents-leap-second-issue/
Ok, but if engineers don't even get enough time from the business
people to read manuals before they code the software then all bets
are off. From a coders point of view 0-6 seems to be more logical
than 1-7. (I personally, e.g., get more complex awk(1) coding
almost always wrong in the first place because of base 1 not 0.)
Me too.
I remember reading somewhere that "Off-by-one errors" are by far the
most prevalent type of bug, no matter the language. There are lots of
variations of it :
Off-by-one error
http://en.wikipedia.org/wiki/Off-by-one_error
One not mentioned, and I see as closely related, is getting the *sign*
inverted. I've found that particularly easy to do in timekeeping code,
for example, applying the Leap Seconds or the initial 10s Leap Second
offset in the wrong direction at some point in the code. Everything can
look just fine until you finally compare it to some known reference to
discover you are off by 10 or the number of Leap Seconds, or something.
Programmers like zero-based because its more mathematically consistent,
but people generally don't like to label the first thing "zero". This
inconsistency is all over the place in society, and been a point of
contention in calendars and timekeeping for centuries.
Programmers have to be careful, duh. And timekeeping systems present a
particularly difficult testing challenge. Its doable, but you've got to
roll up your sleeves and do it. Those business people that might
allocate resources for the effort would hopefully recognize its not as
easy as looks.
Meantime, the "manual" is not easy to read, what with the specifications
scattered all over the place. Its really not rocket science when you get
to the bottom of it but it takes a long time to understand it.
-Brooks
--steffen
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