On 27 February 2015 at 20:02, <dcoffin@xxxxxxxxxxxxxxxxxx> wrote:
> Manuel,
>
> There is no "undefined behavior" here. K&R defined it
> very clearly: Arrays are pointers, and square brackets are
> syntactic sugar for pointer arithmetic and dereferencing:
>
> cam_xyz[i][j] vs. *(cam_xyz + (i)*3 + (j))
Unfortunately, this is simply not true for ISO C, which is the
language that most compilers implement nowadays. And it is easy to
check for yourself:
test.c:445:27: error: incompatible types when assigning to type
'double[3]' from type 'double'
*(cam_xyz + (0)*3 + (j)) = table[i].trans[j] / 10000.0;
^
See also the first answer to
http://stackoverflow.com/questions/25139579/2d-array-indexing-undefined-behavior,
which seems correct, AFAIU.
Neither can you do: **(cam_xyz + (0)*3 + (j)), because cam_xyz has
type 'double (*)[3]' thus **(cam_xyz + 2) is referencing
cam_xyz[2][0].
Cheers,
Manuel.
