Re: if X in 1..35000 versus Boolean

[gautier_niouzes@hotmail.com (Gautier)]

Keith Thompson:

> If I recall correctly (it's been a while), in Pascal you can write
> something like:
> 
>     if X in [1 .. 4] then (* This is Pascal, not Ada *)
>     begin
>         ...;
>     end;
> 
> where [1 .. 4] is a set value constructor.  A naive Pascal compiler
> would build a set value with bits 1, 2, 3, and 4 set, and all other
> bits cleared, and test whether bit X is set.  A more clever Pascal
> compiler might generate code equivalent to X >= 1 and X <= 4.

BTW what "all other bits" means is undefined in Pascal set expression.
Of course it is not the full integer range, otherwise a set
value with integers would be a quite huge object...
In fact Turbo Pascal 6 (1990) or Delphi 6 (2001) seem
to limit the values in sets to 0..255.

    if X in [1 .. 4, 254 .. 255] then ;

passes compilation,

    if X in [1 .. 4, 254 .. 256] then ;
or
    if X in [-1 .. 4] then ;

doesn't!
________________________________________________________
Gautier  --  http://www.mysunrise.ch/users/gdm/gsoft.htm

NB: For a direct answer, address on the Web site!