Interesting bug in number size determination
Sun Apr 18 14:46:00 GMT 1999
From: Szekeres Istvan <email@example.com>
>If I compile this program with -Wall:
> unsigned long u;
> u = 4294967295;
> printf( "%lld\n", u );
> u = 0xffffffff;
> printf("%lld\n", u);
>the compiler says:
>a.c:4: warning: decimal constant is so large that it is unsigned
>(this is for u = 4294967295).
>Shouldn't it fit into an unsigned long?
Yes, but bare numeric literals are signed by default. The compiler is
warning you that it's doing a signed-to-unsigned conversion, which may
not have the results you expect if unsigned long has more than 32 bits.
Add "UL" or "ul" to the end of the number.
>The other interesting thing is that 0xffffffff=4294967295 and it doesn't
>have problems with the hex format :)
The absence of the warning in this case sounds like a genuine bug to
me, albeit a very minor one.
BTW, you're using the wrong print format -- "%lld" is signed long long;
you want "%lu" for unsigned long. EGCS warned about this when I tried
Ross Smith ................................... mailto:firstname.lastname@example.org
.............. The Internet Group, Auckland, New Zealand ..............
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