off-by-one error

from Jargon File (4.4.4, 14 Aug 2003)

off-by-one error
 n.

   [common] Exceedingly common error induced in many ways, such as by
   starting at 0 when you should have started at 1 or vice-versa, or by
   writing < N instead of <= N or vice-versa. Also applied to giving
   something to the person next to the one who should have gotten it.
   Often confounded with {fencepost error}, which is properly a
   particular subtype of it.

from The Free On-line Dictionary of Computing (8 July 2008)

off-by-one error

   <programming> An exceedingly common error induced in many
   ways, such as by starting at zero when you should have started
   at one or vice-versa, or by writing "< N" instead of "<= N" or
   vice-versa.  Often confounded with {fencepost error}, which is
   properly a particular subtype of it.

   [{Jargon File}]

   (1998-09-21)

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