Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!mailrus!ames!hc!lanl!jlg
From: jlg@lanl.gov (Jim Giles)
Newsgroups: comp.lang.fortran
Subject: Re: RE:  An array by any other name. . .
Message-ID: <3641@lanl.gov>
Date: 15 Sep 88 22:25:39 GMT
References: <994@amelia.nas.nasa.gov>
Organization: Los Alamos National Laboratory
Lines: 26

From article <994@amelia.nas.nasa.gov>, by fouts@lemming.nas.nasa.gov.nas.nasa.gov (Marty Fouts):
> x[i] and x+i are semantically equivalent.  It doesn't matter which way
           ^^^
> I say it, they both express a reference to the address of the ith
> element from the start of x.  In some cases, x happens to be a
> pointer, in others not.

x[i] and *(x+i) are semantically equivalent in C.  I don't _want_ them to 
be.  When I ask for an array, I will always use the first syntax.  When
I ask for a pointer, I will always use the second.  With the pointer,
I _don't_ want the language to apply any constraints on where it can
point; with the array I want array bounds checking - that's two different
semantics folks!!!  I _want_ two different semantics, C doesn't provide
it.  The versions of Fortran which presently have a pointer extension
_do_ give me separate semantics for pointers than for arrays.  I hope the
ANSI Fortran committee _doesn't_ standardize on the C model for introducing
pointers - Cray Fortran already has the kind of pointer extension I want.

Furthermore, in C x[i][j] is _supposed_ to be semantically equivalent
to *(*(x+j)+i).  Statically allocated 2-d arrays aren't implemented
this way!  Many versions of dynamically allocated 2-d arrays are.
In order to get a dynamically allocated to behave semantically like
a statically allocated one I have to use a _different_ declaration
syntax.  

J. Giles