java operator and exclusive with boolean operands

Question

can anyone tell me why it prints out 1? I know for sure that true and false AND EXCLUSIVE gives 0. why it enters in if statement?

 public static void main(String[] args) {
    boolean a=true, b=false; 
    int i=0; 
    if(a^b)   {
        i++;
    } 
    System.out.print(i++);
 }

thank you!

http://stackoverflow.com/questions/2646514/what-are-xand-and-xor — SJuan76, Jun 17 '13 at 13:29

score 5 · Accepted Answer · edited May 23 '17 at 10:25

5

You're using xor : ^.

true ^ false == true

See also:

I'm actually not sure what you mean by "exclusive and". See also:

What are XAND and XOR

edited May 23 '17 at 10:25

Community

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answered Jun 17 '13 at 13:29

Lukas Eder

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But I learnt that XOR gives true only when we have 1 and 1 (true , true) , but in this case we have 1 and 0 (false). isn't? – tziuka Jun 17 '13 at 13:32
That's just "AND". As in `&&` or `&` – Lukas Eder Jun 17 '13 at 13:32
`T && T == T`, `T && F == F`, `T ^ T == F`, `T ^ F == T` – BLaZuRE Jun 17 '13 at 13:36

score 2 · Answer 2 · answered Jun 17 '13 at 13:30

2

xor tables

0^0 == 0
0^1 == 1
1^0 == 1
1^1 == 0

So it enters the if statement.

At the end of your main block, after the System.out.println(i++) the i variable will have the value 2 as currently written

answered Jun 17 '13 at 13:30

Stephen Connolly

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score 0 · Answer 3 · answered Jun 17 '13 at 13:29

0

If you talk about ^, it is exclusive or. And for any propositions p1 and p2, p1 ^ p2 is true only if one of p1 or p2 are true.

It is therefore normal that it prints 1.

answered Jun 17 '13 at 13:29

fge

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score 0 · Answer 4 · answered Jun 17 '13 at 13:30

0

In Java the ^ operator is bitwise Exclusive OR, not Exclusive AND. Since true XOR false is TRUE, it enters in the if clause.

I'd suggest for you simply to use == and != operators, if you're dealing with boolean.

answered Jun 17 '13 at 13:30

manub

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In this context it is not the bitwise exclusive or, but the logical exclusive or ;) – fge Jun 17 '13 at 13:31

Anders R. Bystrup · Answer 5 · 2013-06-17T13:47:24.430

0

The ^ operator is exclusive or. The truth table for this is

 XOR  | false true 
-------------------
false | false true
true  | true  false

That's why you get "1" - your if statement evaluates to true.

Cheers,

edited Jun 17 '13 at 13:47

answered Jun 17 '13 at 13:30

Anders R. Bystrup

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java operator and exclusive with boolean operands

5 Answers5