Hanshunping Java note 20th BITS operation shift operation

1. In the case of a signed

The highest bit of the binary is the sign bit, and 1 indicates that the integer 1 represents a negative number

Positive source code Anti-code is the same

Negative number of the anti-code = its source symbol bit unchanged, the other bit to reverse

The complement of a negative number = its anti-code +1

0 's anti-code complement is 0.

Java has no unsigned number, and the number in Java is signed

In a computer operation, it's all in the form of a complement.

2. Bit arithmetic

Bitwise AND &: Two bits are all 1 and the result is 1

Bitwise OR |: Two bits have one of 1 and result is 1

Bitwise XOR: Two-bit one is 0, one is 1, and the result is 1

Bitwise de-0->1:1->0

3. Shift Operations

>> Arithmetic right shift: low overflow, sign bit invariant, and sign bit fill overflow high

<< arithmetic left shift: sign bit unchanged, low fill 0

>>> Logic right SHIFT, low overflow, high fill 0

-2 Original code: 10--010

Anti-code: 11--101

Complement: 11--110

Hanshunping Java note 20th BITS operation shift operation