> x := [chris, pam, mary]; sets bits 1,4,6 *not packed* in x.
> y := [chris] sets bit 1 in y
That should be bits 0,3,5 (enumeration ords are zero based) but otherwise right
> which is why union operators are fast as they are single Op Codes
> Ord(x) = 1 + 8 + 32 = 41
> Ord(y) = 1
You can't get the Ord of a set... this is incorrect...
in the code
type
MySet = (chris, john, bob, mary, fred, pam);
MyXSet = set of MySet;
var
S :MyXSet;
I :Integer;
begin
S := [chris, john, bob];
I := ord(S);
end;
the compiler stops on ord(S) with error incompatible types...
You can get the Ord of an enumeration element not a set. You can however cast
a set to an integer for all enumerations <= 32 elements (with a little fiddling).
type
MySet = (chris, john, bob, mary, fred, pam);
MyXSet = set of MySet;
var
M :Myset;
S :MyXSet;
I :Integer;
P :Pointer;
begin
M := pam; // M is 5, the compiler symbol table enforces type-safety but it's just a 5
I := Integer(M); // I is 5;
I := ord(M); // I is 5;
S := [pam,john,mary,bob];
for M := low(M) to High(M) do if M in S then
ShowMessage(intToStr(ord(M))); // This will show john,bob,mary,pam in this order.
P := @S;
I := Integer(P^) and ((2 shl Ord(High(Myset)))-1); // this should be 2+4+8+32 = 46;
end;
--
Aaron Scott-Boddendijk
Jump Productions
(07) 838-3371 Voice
(07) 838-3372 Fax
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