Re: What is the right way to print a UINTN?

[Laszlo Ersek <lersek@redhat.com>]

On 09/26/16 15:46, Cohen, Eugene wrote:
> Get ready for a potentially stupid question (or at least a question I
> probably should know the answer to by now)...

This is a perfectly valid question.

I print INTN / UINTN values with:
- casting them unconditionally to INT64 / UINT64,
- printing the converted values with the matching conversion specifiers,
such as %Ld (for INT64) and %Lu or %Lx (for UINT64).

This solution requires a bit more typing, and it is a bit pessimistic
for 32-bit builds. On the positive side, it is robust / portable, and
completely valid C.

It is inspired by the standard C types intmax_t / uintmax_t. If you
write portable C code and want to print a value of some integer type,
where the spec only states "signed" or "unsigned integer type", but the
actual type is either implementation defined or unspecified, converting
the value to intmax_t / uintmax_t, and then printing it with %jd vs. %ju
/ %jx, is safe.

Regarding %p (relayed by Alexei as a recommendation from years ago),
that's a bug. %p takes a pointer to void. If we ever enable format
string checking in edk2, for example with GCC's
__attribute__((format(printf, ..., ...))), all those calls will blow up.

Thanks
Laszlo