Sergei Organov wrote:
Herman Geza <[EMAIL PROTECTED]> writes:
[...]
What is the correct way to do this:
void setNaN(float &v) {
reinterpret_cast<int&>(v) = 0x7f800001;
}
without a type-prunning warning? I cannot use the union trick here
Why? Won't the following work?
void setNaN(float &v) {
union { float f; int i; } t;
t.i = 0x7f800001;
v = t.f;
}
As far as I know, this is guaranteed to work with GCC. But it is not
kosher according to language standards, so other compilers might dislike
it. On the other hand, other compilers are not guaranteed to optimize
the call to "memcpy" out either.
Type punning has been disallowed regardless of disguise at least since
Fortran77, when compiler writers realized it had become evil. However,
in my opinion, there's a big difference between a useful little trick
like the union above and the horrible memory overlays that the Fortran77
standard tried to help disambiguate.
Silvius
