Difference between signed and unsigned on bitwise operations

问题

Is there any difference between signed and unsigned variables on bitwise operations?
For example,when dealing with unsigned numbers:
AND 00000111, 00001101
will result 00000101.

But what would happen when dealing with signed numbers?

回答1:

Assuming 2's complement is used for signed numbers, operations that care about signedness (ie they are different for the signed and unsigned interpretation of a bitstring) are:

• division
• modulo
• right shift
• comparisons (except equality)
• double-width multiplication (rare outside of assembly)

Operations for which signedness is irrelevant are:

• addition
• subtraction
• negation (-x means ~x + 1)
• bitwise and
• bitwise or
• bitwise xor
• bitwise not (~x means -x - 1)
• left shift
• multiplication
• comparison (equality only)

回答2:

Unsigned and signed numbers are an interpretation of a bitstring. The AND operator doesn't have that notion and works on the single bits. The result will be the same in any way.

来源：https://stackoverflow.com/questions/13224273/difference-between-signed-and-unsigned-on-bitwise-operations