Re: on using array index, vectorized operation

[Cyrille <comar@eu.adacore.com>]

On Mar 27, 3:31 am, "Nasser M. Abbasi" <n...@12000.org> wrote:
> Hello;
>
> Many times I need to operate on an array using an index
> by doing some operation on the index itself as a variable
> (such as shifting for example).
>
> This below is a very simple example of what I mean.
>
> Given an array A, I might want to do
>
> A(i-1) := A(i)    ----------- (1)
>
> where 'i' above is a variable which contain in it some index
> locations to use to index into the array A.
>
> In Ada, I can do the above, but I am a little clumsy in doing
> it. I know I can use array slicing as in  A(1..4) := A(2..5),
> but wanted to do it when the index itself is a variable, as in (1)
> above. Since in other cases, I have to do more operations on the index
> itself, and so it needs to be in a variable.
>
> This is what I tried so far, and my goal to see if I can
> shorten this more:
>
> ------------------------
> procedure t is
> i: constant array (1..4) of integer:=(2,3,4,5);
> A: array(1..5) of integer := (10,20,30,40,50);
>
> begin
>    --A(2..5) := A(1..4);
>    --A(i-1) := A(i);  --error
>
>    A(i(1)-1..i(4)-1) := A(i(1)..i(4));
> end t;

you can write:

   A(A'First+1 .. A'Last) := A(A'First .. A'Last-1);