Re: ada loops

[Bill Findlay <yaldnifw@blueyonder.co.uk>]

On 30/5/03 16:44, in article
d3ba4d4c.0305300744.520de992@posting.google.com, "Roman V. Isaev"
<rm@gunlab.com.ru> wrote:

> I've got bitten by this (code was translated from pascal by p2ada, so
> please don't bash using goto):
> 
>     for Ijk in 1 .. 40 loop
>        Sss:=Fnmis-Si(Ijk);
>        if  Sss<0.0 then
>           goto Label_1;
>        end if;
>     end loop; --  IJK
>     <<Label_1>>    null;
> 
> Before the loop Ijk is 0, after the loop Ijk is still 0. Huh? Why? I
> replaced Ijk with temp variable and put Ijk := temp before goto and
> it solved the problem, but why we can't have final value when we break
> out of the loop? What's the logic behind this language behaviour?

P2Ada has mis-translated your Pascal program.
In Pascal, the Ijk variable was used and updated by the Pascal for loop.
In Ada, loop-controlled "variables" are actually local constants of the loop
body. Thus your (mis-)translated code has TWO objects called Ijk: the one
appearing outside the loop, and declared by you; and the one appearing
inside the loop and declared by the loop command.

-- 
Bill-Findlay chez blue-yonder.co.uk ("-" => "")