(Crossposted to TP/BP newsgroup too, since it is now about BP too)

Thanks to FPC developper Jonas Maebe, who pointed this out. I often
played with sets, but always of enumerations like enum=(black,white);
which always start on 0, so this bug (also the initial report) was new
for me. (Both the BP as the FPC case, I generally don't know Delphi that
intimate)

If you use sets of subranges, you find most of the differences.
Specially if the ranges go over a multiple of 8.

-----------
{$apptype console} {for delphi. I tested with 4}

type enum1=set of 0..3;
     enum2=set of 1..4;
     enum3=set of 2..5;
     enum4=set of 3..6;
     enum5=set of 4..7;
     enum6=set of 5..8;
     enum7=set of 13..17;
     enum8=set of 15..24;

begin                    {first: BP 7.0 second: Delphi Third: (if
specified: (#elements div 8)}
                          {FPC are all 4}
 writeln(sizeof(enum1));  { 1 1 }
 writeln(sizeof(enum2));  { 1 1 }  
 writeln(sizeof(enum3));  { 1 1}
 writeln(sizeof(enum4));  { 1 1}
 writeln(sizeof(enum5));  { 1 1}
 writeln(sizeof(enum6));  { 2 2 1}
 writeln(sizeof(enum7));  { 2 2 1}
 writeln(sizeof(enum8));  { 3 4 2}

Every set takes the 32 bytes which a full set of 0..255 would need,
minus those bytes which can never contain a member of the actual set,
plus padding from 3 to 4 in Delphi.  Elements div 8 only gives a lower
limit; an extra byte may be needed because of the alignment within the
byte.

P.s. Can Delphi do sets > 256 elements?

--

Jay
--

TBits gives a resizeable array [0..Size-1] of BIT, but as a replacement
for "set" it is rather severely (IMHO) handicapped by an apparent
complete lack of anything resembling a set operation.  It does have a
means of locating the first "0" bit.

I suppose one could define procedures & functions on TBits corresponding
to set operators - they should IMHO be impressively slow.

It should be better, though maybe less general, to use an array of sets
- cf. my pas-opt1.htm "Larger Sets".