How to iterate over a range with a custom step?

Question

How can I iterate over a range in Ada with a custom step ?

For I in Integer'Range
loop
    -- do something every 10 steps
end loop;

Can I define a subtype with specific step ?

Answer 1

Typically one does an explicit increment:

declare
   I : T := Start;
begin
   loop
      exit when I > Stop;

      -- do something every Step steps
      I := I + Step;
   end loop;
end;

Sometimes you need a slightly different test:

declare
   I : T := Start;
begin
   loop
      -- do something every Step steps

      exit when I > Stop - Step;

      I := I + Step;
   end loop;
end;

when that last increment will overflow. Or you can handle the exception.