Re: How to make like Fortran "do i = 1,20,2"

[Kilgallen@eisner.decus.org.nospam (Larry Kilgallen)]

In article <8lpcbe$40n$1@news.uit.no>, reinert@ola.npolar.no (Reinert Korsnes) writes:
> 
> Hi,
> 
> How can one in Ada elegantly make a loop through each 2 element of an array ?  
> I am looking for something like: "do i = 1,20,2" in Fortran, or
> 
> for I in A'range ("step 2") loop
>    something...
> end loop;

===========

for I in A'range loop
    if (I - A'first) mod 2 = 0
    then
        null;
    end if;
end loop;

But of course that does nothing to ensure that A'length is an even number.

===========

for I2 in A'first/2 .. A'last/2 loop
    declare
        I : INTEGER := I2*2;
    begin
        null;
    end;
end loop;

That approach will have problems if either A'length is an odd
number or if either limit of A'range is an odd number.

===========

But what does Fortran do in those negative and odd number cases ?