Puzzle - RPL and others

[3298]

(05-11-2021 11:58 AM)Albert Chan Wrote:  Without typecast, it may already be broken with left shift 31

1 << 31 = -2147483648

If bitset_t is 32-bits, not harm done, digit_bitset = 0x80000000
If bitset_t is 64-bits, it messed up, digit_bitset = 0xffffffff80000000

That would be sign-extension. I typedef'd bitset_t to be unsigned long long, which should as an unsigned type receive zero-extension instead. Anyway, a shift of 31 only occurs when the base hits 33, and since 33 (as an odd number) is treated with an early exit, the program would run into the undefined result of a shift by 32 at the same time (starting from base=34).

Perhaps I should've picked a more forgiving language for the port to a more powerful platform, like, say, Haskell ... C is certainly happy to stab you in the back when you treat it wrong.