Java: Binary (original code, inverse code, complement) and bitwise operations

One or two binary (original code, anti-code, complement)

• The highest bit of binary is the sign bit ("0" represents a positive number, "1" represents a negative number);
• There are no unsigned numbers in Java ;
• The computer is computed with the complement of integers;

1. Original code: Converts an integer to a binary representation

In the case of type int, theint type is 4 bytes and a total of 32 bits .

For example, 2 of the original code is:00000000 00000000 00000000 00000010

-2 of the original code is:10000000 00000000 00000000 00000010

2. Anti-code

Inverse code for positive numbers: same as original code

Negative anti-code: The original code of the symbol bit unchanged, the other bits take the reverse

For example, the counter code of 2 is:11111111 11111111 11111111 11111101

3. Complement

The complement of positive numbers: Same as the original code

Complement of negative numbers: Anti-code +1

For example, the complement of 2 is:01111111 11111111 11111111 11111110

Second, bitwise operations

There are 4 bitwise operators in Java:

1.bitwise AND &:Two bits are 1 and the result is 1

For example, 2&3 = 2

2 The original code is: 00000000 00000000 00000000 00000010

3 The original code is: 00000000 00000000 00000000 00000011

2&3 The original code: 00000000 00000000 00000000 00000010 = 2

2.bitwise OR |:At least one bit is 1 and the result is 1

For example, 2|3 = 3

2 The original code is: 00000000 00000000 00000000 00000010

3 The original code is: 00000000 00000000 00000000 00000011

2|3 The original code: 00000000 00000000 00000000 00000011 = 3

3.Bitwise XOR or ^:Two bits one is 1, one is 0, and the result is 1

For example, 2|3 = 3

2 The original code is: 00000000 00000000 00000000 00000010

3 The original code is: 00000000 00000000 00000000 00000011

2^3 The original code: 00000000 00000000 00000000 00000001 = 1

4.Bitwise Counter ~:0 becomes 1, 1 becomes 0

For example, = 3

Reverse 2 of the original code: 11111111 11111111 11111111 11111101 (the complement of the reversed result, that is, the complement of 3.) We need to release the original code from the complement to get-3)

Convert to Counter code: 11111111 11111111 11111111 11111100 (complement minus 1)

Converted to original code: 10000000 00000000 00000000 00000011 =-3 (the symbol is the same, the other bits take the reverse)

Summarize

1. Positive numbers of the original code, anti-code, and complement are the same;
2. Negative number of the inverse code = The original code of the symbol bit unchanged, the other bits take the reverse;
3. The complement of negative number = inverse code +1;
4. 0 of the original code, anti-code, complement is 0;
5. The computer is operated in the complement;
6. The inverse is different from the inverse code;

2018-01-06 18:38:29

Java: Binary (original code, inverse code, complement) and bitwise operations