What is C# exclusive or `^` usage?

Question

Can anyone explain this operator with a good example?

I know what this operator is. I mean a real-life example.

Simple search: https://secure.wikimedia.org/wikipedia/en/wiki/Exclusive_or — thekip, Jun 21 '11 at 08:24
I gave 3 in my answer. There are about a dozen on the wiki page. — Merlyn Morgan-Graham, Jun 21 '11 at 08:31
For the first time in my entire programming career, I've found a use for the XOR operator. Having ^ for Math.Pow() would have been a MUCH better use of the symbol. — Dan W, Apr 28 '15 at 08:40

score 18 · Accepted Answer · edited Jun 20 '20 at 09:12

It is an implementation of the the logical operation exclusive disjunction

http://en.wikipedia.org/wiki/Exclusive_or

Exclusive disjunction is often used for bitwise operations. Examples:

1 xor 1 = 0

1 xor 0 = 1

0 xor 1 = 1

0 xor 0 = 0

1110 xor 1001 = 0111 (this is equivalent to addition without carry)

As noted above, since exclusive disjunction is identical to addition modulo 2, the bitwise exclusive disjunction of two n-bit strings is identical to the standard vector of addition in the vector space (Z/2Z)^4.

In computer science, exclusive disjunction has several uses:

It tells whether two bits are unequal.

It is an optional bit-flipper (the deciding input chooses whether to invert the data input).

It tells whether there is an odd number of 1 bits ( is true iff an odd number of the variables are true).

(and a whole ton of other uses)

score 14 · Answer 2 · edited Mar 18 '16 at 21:04

14

For example, like this:

var result = a ^ b;

result          a        b
--------------------------------
true            true    false
true            false   true
false           true    true
false           false   false

edited Mar 18 '16 at 21:04

Peter Mortensen

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answered Jun 21 '11 at 08:27

shenhengbin

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score 7 · Answer 3 · answered Jun 21 '11 at 08:32

7

For "exclusive or" to evaluate to true one and only one operand has to be true.

foo ^ bar

is equivalent to

(foo && !bar) || (!foo && bar)

answered Jun 21 '11 at 08:32

Till

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and @shenhengbin your answers about evaluating boolean values with the exclusive or operator made me wonder: isn't doing `foo ^ bar` equivalent to `foo != bar` as well then? – T_D Apr 27 '20 at 15:37

score 2 · Answer 4 · edited Aug 31 '23 at 08:57

2

When using XOR, the statement only evaluates to true if only ONE of the compared statements is true. So:

bool foo = true;
bool bar = false;
if (foo ^ bar) { bar = true;} // this evaluates to true 
bool baz = foo ^ bar; // This evaluates to false, since both statements are now true.

edited Aug 31 '23 at 08:57

gehho

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answered Jun 21 '11 at 08:24

Andreas Eriksson

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score 1 · Answer 5 · edited Mar 18 '16 at 21:03

A programming language's reference is always the best place to look for the definitions of operators.

In this case, MSDN is the most appropriate definition for a C# operator.

According to the documentation:

Binary ^ operators are predefined for the integral types and bool. For integral types, ^ computes the bitwise exclusive-OR of its operands. For bool operands, ^ computes the logical exclusive-or of its operands; that is, the result is true if and only if exactly one of its operands is true.

An example is also listed.

score 1 · Answer 6 · answered Jun 21 '11 at 08:27

1

XOR is a common boolean operator and has nothing unique to it in C#. I suggest reading a little about boolean algebra to learn what it is used for with 1 bit, then check what you get when you do (a XOR b) XOR b with any two numbers or characters a and b.

answered Jun 21 '11 at 08:27

Danny Varod

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What is C# exclusive or `^` usage?

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