From: Matthew J Heaney <mheaney@on2.com>
Subject: Re: How to make like Fortran "do i = 1,20,2"
Date: 2000/07/27
Date: 2000-07-27T00:00:00+00:00 [thread overview]
Message-ID: <7rhf9bb362.fsf@butter.albany.duck.com> (raw)
In-Reply-To: 39805669.3E7CF6CF@lmtas.lmco.com
Gary Scott <Gary.L.Scott@lmtas.lmco.com> writes:
> Hmmm, these and similar examples posted do not make Ada look very
> elegant...it makes a very simple concept seem somewhat convoluted.
This "very simple concept" is a major source of bugs -- that's why it's
not in the language.
If you want to increment by 2 through the loop, it's simple enough:
declare
I : Positive := A'First;
begin
while I <= A'Last loop
... A(I) ...
I := I + 2;
end loop;
end;
QED
If you want to do odd-ball things, then sometimes that requires extra
work. The common things (like incrementing the loop index by 1) are
easy to do.
I can't even remember the last time I had to iterate over an array by an
increment other than 1.
Consider this analogy. Suppose you want to iterate over a linked list:
list<int> intList;
...
list<int>::iterator iter = intList.begin();
In the normal case, when you increment by 1, it's simple:
while (iter != intList.end())
{
...
iter++;
}
Asking how to iterate in increments of 2 is like asking, How do I visit
every other list element? That's an odd-ball thing to do, so you have
to do extra work. (Try it and you'll see.)
next prev parent reply other threads:[~2000-07-27 0:00 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2000-07-27 0:00 How to make like Fortran "do i = 1,20,2" Reinert Korsnes
2000-07-27 0:00 ` G. de Montmollin
2000-07-27 0:00 ` Lutz Donnerhacke
2000-07-27 0:00 ` Ken Garlington
2000-07-27 0:00 ` des walker
2000-07-27 0:00 ` tmoran
2000-07-28 0:00 ` Reinert Korsnes
2000-07-28 0:00 ` Gautier
2000-07-29 0:00 ` tmoran
2000-07-27 0:00 ` Gary Scott
2000-07-27 0:00 ` Larry Kilgallen
2000-07-27 0:00 ` Gary Scott
2000-07-27 0:00 ` Larry Kilgallen
2000-07-27 0:00 ` mjsilva
2000-07-27 0:00 ` Matthew J Heaney [this message]
2000-07-28 0:00 ` Gary Scott
2000-07-28 0:00 ` mjsilva
2000-07-29 0:00 ` Ehud Lamm
2000-07-28 0:00 ` Richard Riehle
[not found] ` <39833637.3B83BFAC@lmtas.lmco.com>
2000-07-29 0:00 ` Gary Scott
2000-07-29 0:00 ` Robert I. Eachus
2000-07-27 0:00 ` Pat Rogers
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