You can pass a negative number such that num * 64 will underflow and result in a large positive number. (Technically it's UB, but in practice it will probably u

You can pass a negative number such that num * 64 will underflow and result in a large positive number. (Technically it's UB, but in practice it will probably underflow). Or as someone else mentions, even without underflow, it will be converted to unsigned since malloc takes a size_t.