Path: utzoo!attcan!uunet!mcvax!botter!star.cs.vu.nl!dick
From: dick@cs.vu.nl (Dick Grune)
Newsgroups: comp.misc
Subject: Programming style with arrays, enquiry
Keywords: programming style, arrays
Message-ID: <724@dick.cs.vu.nl>
Date: 14 May 88 20:28:14 GMT
Organization: V.U. Informatica, Amsterdam, the Netherlands
Lines: 45


On the subject of programming style (a constant worry of mine), I should like
to ask two (related) questions to the general programming public.

When handling arrays, the bounds have to be described in some way.
I know of three (consistent) methods to do so:

1.  Address of first item and length.
This is clean and can handle zero-length arrays.  It gives, however, rise to
incessant additions, since one wants the upper limit much more often than the
length:
	if (p > array + length)  error();
(or is it
	if (p >= array + length)  error();
?)

2.  Address of first item and address of last item.
This seems natural but you get +1 and -1 all over the place; I can hardly ever
get this right and I have just given up correcting a piece of code someone
else wrote in this style.

3.  Address of first item and address of first non-item.
This is unnatural and does not fit with everyday language, but it works.  My
code gets simpler (duller if you will), no more funny adjustments, the length
of the array is the difference of the bounds, etc.  The only problem with it
is that there does not seem to be natural word or identifier for the first
non-item (= the item after the last one).

So my questions are:

I.	What do you use normally?  and

II.	If you use method 3, what do you call the item past the last item?

I will summarize to the net.
(If it isn't clear yet, I use method 3 and clumsy names for the last plus one
element).

					Dick Grune
					Vrije Universiteit
					de Boelelaan 1081
					1081 HV  Amsterdam
					the Netherlands
					dick@cs.vu.nl
					...!mcvax!vu44!dick