Re: "undefined behavior"?

Malcolm McLean <malcolm.arthur.mclean@gmail.com> writes:

On 13/06/2024 19:01, bart wrote:

And here it just gets even uglier. You also get situations like this:
     uint64_t i=0;
     printf("%lld\n", i);
This compiles OK with gcc -Wall, on Windows64. But compile under Linux64
and it complains the format should be %ld. Change it to %ld, and it
complains under Windows.
It can't tell you that you should be using one of those ludicrous macros.
I've also just noticed that 'i' is unsigned but the format calls for
signed. That may or may not be deliberate, but the compiler didn't say
anything.
>

Exactly. We can't have this just to print out an integer.

This is how C works.  There's no point in moaning about it.  Use another
language or do what you have to in C.

In Baby X I provide a function called bbx_malloc(). It's is guaranteed
never to return null. Currently it just calls exit() on allocation failure.
But it also limits allocation to slightly under INT_MAX. Which should be
plenty for a Baby program, and if you want more, you always have big boy's
malloc.

And if you need to change the size?

But at a stroke, that gets rid of any need for size_t,

But sizeof, strlen (and friends like the mbs... and wcs... functions),
strspn (and friend), strftime, fread, fwrite. etc. etc. all return
size_t.

For people taught to ignore size_t, care is also needed when calling
functions that take size_t arguments as the signed to unsigned
conversion can cause surprises when not flagged by the compiler.  I
don't know if I am right, but I would bet that many of the "don't bother
with size_t" crowd are also in the "don't bother with all those warning
flags to the compiler" crowd.

and long is very
special purpose (it holds the 32 bit rgba values).

Isn't that rather wasteful when long is 64 bits?

--
Ben.