Contiguous Arrays

[Badri Lokanathan]

> In article <2508 at ssc-vax.UUCP>, dmg at ssc-vax.UUCP (David Geary) writes:
> >   Are ALL arrays in C contiguious?  If I declare an array:
> > 
> >   int  x[10];
> > 
> >   am I GUARANTEED that x[0] through x[9] will occupy contiguous memory,
> >   or is the compiler free to scatter the elements around in memory?

In article <8943 at alice.UUCP>, ark at alice.UUCP (Andrew Koenig) writes:
> You are guaranteed that if you say
> 
> 	int *p;
> 
> 	p = &x[k];		/* 0 <= k < 9 */
> 	p++;
> 
> then p now points to x[k+1].  It is possible to execute `p++' in
> a separately compiled routine.

On a similar note, just yesterday a friend and I were discussing
tricks to access arrays with different ranges.
For instance, if the array was to be x[101] to x[110] instead of
x[0] to x[9], what is the easiest way to do it?
For automatic arrays one could do
int space[10], *x; 
x = &space[0] - 101;

For malloc'd arrays, one could do something like

int *make_array(init_index,final_index)
int init_index, final_index;
{
	int *foo;

	foo = (int *) malloc((unsigned) (final_index-initial_index+1));
	return (foo - init_index);
}

Kind of ugly; only a pascal programmer would think of such grossness (:-)

In any case, I am hard pressed to think of reasons for wanting
to store an automatic array in non-contiguous space.
-- 
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