What does a circled plus mean?

Answer 1

Hi

Its not an addition, but an exclusive OR operation. At least the output confirms to the same, so the symbol of the operator.

cheers

Answer 2

The plus-symbol in a circle does not denote addition. It is a XOR operation.

I hope it makes more sense now..

Answer 3

This is not an plus, but the sign for the binary operator XOR

a   b   a XOR b
0   0   0
0   1   1
1   0   1
1   1   0

Answer 4

That's the XOR operator, not the PLUS operator

XOR works bit by bit, without carrying over like PLUS does

1 XOR 1 = 0
1 XOR 0 = 1
0 XOR 0 = 0
0 XOR 1 = 1

Answer 5

People are saying that the symbol doesn't mean addition. This is true, but doesn't explain why a plus-like symbol is used for something that isn't addition.

The answer is that for modulo addition of 1-bit values, 0+0 == 1+1 == 0, and 0+1 == 1+0 == 1. Those are the same values as XOR.

So, plus in a circle in this context means "bitwise addition modulo-2". Which is, as everyone says, XOR for integers. It's common in mathematics to use plus in a circle for an operation which is a sort of addition, but isn't regular integer addition.

Answer 6

It's an exclusive or (XOR). If I remember correctly, when doing bitwise mathematics the dot (.) means AND and the plus (+) means OR. Putting a circle around the plus to mean XOR is consistent with the style used for OR.

Answer 7

I used the logic in the replies by rampion and schnaader. I will summarise how I confirmed the results. I changed the numbers to binary and then used the XOR-operation. Alternatively, you can use the Hexadecimal tables: Click here!