13 May
2005
13 May
'05
5:01 p.m.
a[++i] = ++i;
I assume that the above statement could have two possible
interpretations:
(a) j = ++i; k = ++i; a[j] = k;
(b) j = ++i; k = ++i; a[k] = j; (i) Are there any other interpretations?
Yes.
If so, what is the equivalent code?
There may not be any. When code wanders into realms specified to
produce undefined behaviour (as here, where i is modified twice without
an intervening sequence point), there is nothing compelling the
compiler to produce output that corresponds to any well-formed C code
at all. (I'm not even sure there's anything in the C spec calling for
the compiler to produce *any* output in such circumstances.)
If you want possible interpretations that *do* correspond to writable C
code, here's one for you:
a[i*i]=314156; i=a[0]/a[-1];
(Of course, a real compiler would be unlikely to do that....)
(ii) Does gcc 3.3 produce a warning or an error
message?
I don't know (and mostly don't care).
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