«

I have this code:

#include <iostream>

using namespace std;

#define DeclareEnumTricks(T) \
inline T& operator++(T& e) \
{ \
e = T(e+1); \
return e; \
} \
\
inline T operator++(T& e, int) \
{ \
T old = e; \
e = T(e+1); \
return old;\
} \
\
inline T& operator--(T& e) \
{ \
e = T(e-1); \
return e; \
} \
\
inline T operator--(T& e, int) \
{ \
T old = e; \
e = T(e-1); \
return old; \
} \
\
inline T end(T) \
{ \
return T##_end; \
} \
\
inline T begin(T) \
{ \
return T##_begin; \
}

enum Piece {none,pawn,knight,bishop,rook,queen,king,
Piece_begin = pawn, Piece_end = king + 1};
DeclareEnumTricks(Piece)

int main()
{
Piece p = none;
cout << p << " " << p++ << " " << ++p << endl;
}

The output from g++ and several other compilers is _not_

0 0 2

as expected. In g++ it is

2 1 1

Is there a bug in the code, or in the compilers?

/David

> cout << p << " " << p++ << " " << ++p << endl;
> Is there a bug in the code, or in the compilers?

In the FAQ.

Fao, Sean wrote:
>> cout << p << " " << p++ << " " << ++p << endl;
>>Is there a bug in the code, or in the compilers?
>
>
> In the FAQ.

Thanks. I've looked, but I can't find anything relevant. Could be more
specific?

/David

"David Rasmussen" <> wrote in message
news:bu6u3g$sv6$...
> I have this code:
>
> #include <iostream>
>
> using namespace std;
>
> #define DeclareEnumTricks(T) \
> inline T& operator++(T& e) \
> { \
> e = T(e+1); \
> return e; \
> } \
> \
> inline T operator++(T& e, int) \
> { \
> T old = e; \
> e = T(e+1); \
> return old;\
> } \
> \
> inline T& operator--(T& e) \
> { \
> e = T(e-1); \
> return e; \
> } \
> \
> inline T operator--(T& e, int) \
> { \
> T old = e; \
> e = T(e-1); \
> return old; \
> } \
> \
> inline T end(T) \
> { \
> return T##_end; \
> } \
> \
> inline T begin(T) \
> { \
> return T##_begin; \
> }
>
> enum Piece {none,pawn,knight,bishop,rook,queen,king,
> Piece_begin = pawn, Piece_end = king + 1};
> DeclareEnumTricks(Piece)
>
> int main()
> {
> Piece p = none;
> cout << p << " " << p++ << " " << ++p << endl;
> }
>
> The output from g++ and several other compilers is _not_
>
> 0 0 2
>
> as expected. In g++ it is
>
> 2 1 1
>
> Is there a bug in the code, or in the compilers?
>
> /David


Comeau C++ came up with the expected output: 0 0 2

Sumit Rajan wrote:
>
> > int main()
> > {
> > Piece p = none;
> > cout << p << " " << p++ << " " << ++p << endl;
> > }
> >
> > The output from g++ and several other compilers is _not_
> >
> > 0 0 2
> >
> > as expected. In g++ it is
> >
> > 2 1 1
> >
> > Is there a bug in the code, or in the compilers?
> >
> > /David
>
> Comeau C++ came up with the expected output: 0 0 2

Doesn't matter what's expected. What matters is what's required. The
behavior of the program is undefined. Anything goes.

--

Pete Becker
Dinkumware, Ltd. (http://www.dinkumware.com)

"David Rasmussen" <> wrote in message
news:bu6vfe$tb8$...
> Fao, Sean wrote:
> >> cout << p << " " << p++ << " " << ++p << endl;
> >>Is there a bug in the code, or in the compilers?
> >
> >
> > In the FAQ.
>
> Thanks. I've looked, but I can't find anything relevant. Could be
more
> specific?
>

I couldn't either. Try this:

http://www.langer.camelot.de/Article...ncePoints.html

Jonathan

osmium wrote:
> David Rasmussen writes:
>
>
>> cout << p << " " << p++ << " " << ++p << endl;
>
> Did you allow for the fact that shift left has a lower precedence than
> postfix ++ and prefix ++?
>

Even if, the first p should print out as 0. Shouldn't it?

/David

Pete Becker wrote:
>
> Doesn't matter what's expected. What matters is what's required. The
> behavior of the program is undefined. Anything goes.
>

I would sure like to know why...

/David

David Rasmussen wrote:

> Fao, Sean wrote:
>>> cout << p << " " << p++ << " " << ++p << endl;
>>>Is there a bug in the code, or in the compilers?
>>
>>
>> In the FAQ.
>
> Thanks. I've looked, but I can't find anything relevant. Could be more
> specific?

I thought I had seen it in the C++ FAQ at one time but I might just be
dreaming. Oh well, it's in the C FAQ for the same reason...

http://www.eskimo.com/~scs/C-faq/s3.html

Thanks!

I don't know what I was thinking. I know about the sequencing point type
problem. My mind was focused on the macros. I was sure I had some bug.

/David