When should you use bitwise operators?

Bitwise operators are good for saving space -- but many times, space is hardly an issue. And one problem with working at the level of the individual bits is that if you decide you need more space or want to save some time -- for instance, if we needed to store information about 9 cars instead of 8 -- then you might have to redesign large portions of your program. On the other hand, sometimes you can use bitwise operators to cleverly remove dependencies, such as by using ~0 to find the largest possible integer. And bit shifting to multiply by two is a fairly common operation, so it doesn't affect readability in the way that advanced use of bit manipulation can in some cases (for instance, using XOR to switch the values stored in two variables).

There are also times when you need to use bitwise operators: if you're working with compression or some forms of encryption, or if you're working on a system that expects bit fields to be used to store boolean attributes.