Marco van de Voort wrote:
>
> How (and if so, for what types) is low() and high() defined in ISO
Pascal
> (old and extended) ?
>
> Discussion piece was this workaround for testing members in a set that
was
> defined using an anonymous enumeration, that fails in Delphi because
> high and low are not defined for set. It did work in FPC, probably
because
> it is defined there.
>
> { imagine that this type is given, e.g. in a different module}
> type myset = set of ( a1,a2,a3,a4,a5,a6);
>
> { the rest is effectively the workaround }
> const
> beginmyset=ord(low(myset));
> endmyset=ord(high(myset));
> type
> uglyenum = beginmyset..endmyset;
> uglyset= set of uglyenum;
>
> var b : myset;
> i : integer;
>
> begin
> b:=[a1,a2,a3];
> for i:=ord(low(myset)) to ord(high(myset)) do
> if i in uglyset(b) then writeln(i);
> end.
Wouldn't the ord (a1) always be equal 0?
A possible work around might be
const
HiMySet = 8 * sizeof (myset);
Of course HiMySet will overshoot by some bits but now with
type uglyenum = 0..HiMySet-1;
{and} uglyset = set of uglynum;
b:=[a1,a2,a3];
for i := 0 to HiMySet do
if i in uglyset (b)
then writeln (i);
the correct orders for the elements a1, a2 and a3 are written out. I can
see a potential problem if the unused hi bits of a "myset" are not set
to zero by the compiler.
Cheers Hanford
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