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From: Matthew Heaney <matthew_heaney@acm.org>
Subject: Re: Software landmines (loops)
Date: 1998/09/01
Message-ID: <m34suspy68.fsf@mheaney.ni.net>#1/1
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NNTP-Posting-Date: Mon, 31 Aug 1998 22:40:57 PDT
Newsgroups: comp.lang.eiffel,comp.object,comp.software-eng,comp.lang.ada
Date: 1998-09-01T00:00:00+00:00
List-Id: <comp.lang.ada>

reilly@zeta.org.au (Andrew Reilly) writes:

> I mostly do numerics, and find myself wanting something much simpler
> than the current styles, with a simple integer iteration count.
> A bit like the old Fortran do loops.  Even having to name and
> declare a loop variable is overhead (semantic baggage) I'd avoid
> if I could.

Then Ada's your language!  Although you have to name a loop variable (in
a for loop), you don't have to acually declare it via a type
declaration.  

For example, to iterate over an array, you do this

   A : Integer_Array;
begin
...
   for Index in A'Range loop
       ... A (Index) ...

This works even for the case of an array whose length is zero.

In the stack example, I showed how to iterate over a portion of the
array:

   for Index in Positive range 1 .. L.Top loop
      if L.Items (Index) /= R.Items (Index) then ...

There are other features of Ada95 (the Numerics annex, for example, and
being able to call existing Fortran code) that would appeal to a Fortran
guy.