OR, AND Operator

Question

Newbie question. How to calculate the value of the formula A f B, where f - the binary function OR or AND?

Fortify

Do you mean boolean, or binary operation? – Thyrse

Answer 1

There is a distinction between the conditional operators && and || and the boolean operators & and |. Mainly it is a difference of precendence (which operators get evaluated first) and also the && and || are 'escaping'. This means that is a sequence such as...

cond1 && cond2 && cond3

If cond1 is false, neither cond2 or cond3 are evaluated as the code rightly assumes that no matter what their value, the expression cannot be true. Likewise...

cond1 || cond2 || cond3

If cond1 is true, neither cond2 or cond3 are evaluated as the expression must be true no matter what their value is.

The bitwise counterparts, & and | are not escaping.

Hope that helps.

Tarr

I think you mean the bitwise counterparts, not the boolean counterparts. – Abad

Answer 2

Logical OR is ||, logical AND is &&. If you need the negation NOT, prefix your expression with !.

Example:

X = (A && B) || C || !D;

Then X will be true when either A and B are true or if C is true or if D is not true (i.e. false).

If you wanted bit-wise AND/OR/NOT, you would use &, | and ~. But if you are dealing with boolean/truth values, you do not want to use those. They do not provide short-circuit evaluation for example due to the way a bitwise operation works.

Abad

According to MSDN Logical OR is | and Logical AND is &. Where as Conditional OR is || and Conditional AND is &&. Source: msdn.microsoft.com/en-us/library/6a71f45d.aspx – Landlubber

Ugh, that's terrible wording. Why can't they just call it "Binary OR/AND"? – Abad

Answer 3

if(A == "haha" && B == "hihi") {
//hahahihi?
}

if(A == "haha" || B != "hihi") {
//hahahihi!?
}

Gondola

Answer 4

I'm not sure if this answers your question, but for example:

if (A || B)
{
    Console.WriteLine("Or");
}

if (A && B)
{
    Console.WriteLine("And");
}

Oberammergau

Your example would never reach the && evaluation unless A && B are false, in which case it would never pass the 2nd statement. – Perk

@Perk - That's not true unless Console.WriteLine() does a thread abort I don't know about? :) – Thyrse

LOL @James... perhaps he thought it was an if/else or something. – Salazar

If A or B is true and the other is false the console output would be "Or". If A and B are true, the console output would be "Or", "And". Otherwise nothing. Not sure what the talk about thread abort is all about...?! – Tarr

Yes - sorry folks - the first answer was an if / else. I realised my mistake and corrected. Sorry, @Perk :-) – Oberammergau

Answer 5

Use '&&' for AND and use '||' for OR, for example:

bool A;
bool B;

bool resultOfAnd = A && B; // Returns the result of an AND
bool resultOfOr = A || B; // Returns the result of an OR

Latrice

Answer 6

If what interests you is bitwise operations look here for a brief tutorial : http://weblogs.asp.net/alessandro/archive/2007/10/02/bitwise-operators-in-c-or-xor-and-amp-amp-not.aspx .bitwise operation perform the same operations like the ones exemplified above they just work with binary representation (the operation applies to each individual bit of the value)

If you want logical operation answers are already given.

Athletic

Answer 7

&& it's operation return true only if both operand it's true which implies

bool and(bool b1, bool b2)]
{
 if(b1==true)
 {
   if(b2==true)
    return true;
 }
 return false;
}

|| it's operation return true if one or both operand it's true which implies

bool or(bool b1,bool b2)
{
 if(b1==true)
 return true;
 if(b2==true)
 return true;
 return false;
}

if You write

y=45&&34//45 binary 101101, 35 binary 100010

in result you have

y=32// in binary 100000

Therefore, the which I wrote above is used with respect to every pair of bits

Anemology

Your last paragraph is incorrect. That would be true for bitwise and (&) but certainly not for boolean and. – Abad

Answer 8

many answers above, i will try a different way:

if you are looking for bitwise operations use only one of the marks like:

3 & 1 //==1 - and 4 | 1 //==5 - or

Alicaalicante