Can I ensure that a variable will contain just one value using bitwise and without if statements?

[alpine lantern]

I'm beeing introduced to bitwise operators and I know that it performs a certain operation in each bit of a variable.

Can I ensure that this variable will contain only the value 3 using any bitwise operation?

// if i==3: ((0) + 3) & 3 == 0b11 & 0b11 == 0b11
int mod3 = ((i % 3) + 3) & 3;

Testing:

int mod3 = (5) & 3              //0b101 & 0b011 == 0b001 -> mod3 == 1?

[noble oasis]

<@&987246883653156906> please have a look, thanks.

[noble oasis]

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[viral quail]

i == 3 ?

[alpine lantern]

Yes, presuming that i==3 in this case

[viral quail]

I don't understand your question

[alpine lantern]

I'm asking if I could make a variable to only contain one single value. Like, if I want it to only contain the value 3, I would do (if possible) a bitwise operation in order to ensure that.

Example

int i shouldBeThreeOrZero = ((i % 3) + 3) & 3;

I think I'll try to search for it, it's hard to ask

[viral quail]

Why can't you just do I == 3

[alpine lantern]

Because that's a boolean operation and would return 1 or 0, witch cannot be stored in a integer

And I cannot use if's or ternary if's

[viral quail]

And for what will you use the result ?

Also, if you want 0 if it is a 3, otherwise any number:

int isThree = i - 3;

If you really want that is 0 if it is a 3, but 1 if it isn't:

int isThree = i - 3 & 1;

[alpine lantern]

This is the piece of code. FizzBuzz without direct if's (Boolean.compare.... has if's I know)

I know it's not the most optimal solution, but I haven't searched anything yet, so give it a credit

I'm having problems because not all values in the output are correct

Some of them are

[viral quail]

Why are you doing i % 3 +3

If I is 6, it is true

Just do a subtraction

[viral quail]

And that's cheating

[alpine lantern]

In order to access the HashMap key

only [3] : "Fizz"
only [5]: "Buzz"
both [3+5]: "FizzBuzz"

[alpine lantern]

I'll figure it out

[inland prism]

What are you trying to achieve? FizzBuzz without if?

[alpine lantern]

Yes

But there still are indirect if's in some methods I've called

[flat gust]

@alpine lantern i took a shot at it if you want to see

[inland prism]

You're going to be using conditionals at some point

It's possible to fit a FizzBuzz within a for loop, even without a body

You'd use ternary expressions

[alpine lantern]

Please, I do.

I found this interesting article:
http://philcrissman.net/posts/eulers-fizzbuzz/

[alpine lantern]

@ dioxin

[flat gust]

public class Main {

    public static void main(String[] args) {
        for (int i = 0; i < 100; i++) {
            interface Fizzer {
                void fizz(int i);
            }


            var fizzers = new Fizzer[] {
                    (__) -> System.out.println("fizzbuzz"),
                    (__) -> System.out.println("fizz"),
                    (__) -> System.out.println("buzz"),
                    System.out::println
            };
            var fizzups = new int[] {0, 1, 1};
            var fizzies = new int[] {0, 2, 2, 2, 2};

            fizzers[fizzups[i % 3] + fizzies[i % 5]].fizz(i);
        }
    }
}

@alpine lantern There is still an if for the for loop

i have a few ideas for how to get rid of that

[inland prism]

That's interesting

[alpine lantern]

impressive

I'll need minutes to understand that, I've not studied yet lambdas, method references and some stuff

var fizzups = new int[] {0, 1, 1};
var fizzies = new int[] {0, 2, 2, 2, 2};
Why is this?

[flat gust]

look at the first arra

it indexes the possible results of i % 3 to a number

1 + 2 means neither i % 3 or i % 5 match

[alpine lantern]

Why the number 2 isn't there?

Shoudn't k % 3 produce results [0..2]?

[flat gust]

nonono

the index is [0..2]

just step through it

[alpine lantern]

Oh, okay

I'll need some time to read and understand it all

Thanks

Oh, and where is the fizz() method?

(__) -> System.out.println("fizzbuzz"),
(__) -> System.out.println("fizz"),
(__) -> System.out.println("buzz"),

are this functions its definition?

I think I got it

[viral quail]

you could have just used strings instead of an interface

[flat gust]

for the fizzbuzz parts, but then you'd need an if to print the actual value

could have changed the interface to return a string and gotten rid of the duplicate printlns tho

[viral quail]

Ah yes, something like that

public class Main {

    public static void main(String[] args) {
        for (int i = 0; i < 100; i++) {
            interface Fizzer {
                String fizz(int i);
            }


            var fizzers = new Fizzer[] {
                    _ -> System.out.println("fizzbuzz"),
                    _ -> System.out.println("fizz"),
                    _ -> System.out.println("buzz"),
                    String::valueOf
            };
            var fizzups = new int[] {0, 1, 1};
            var fizzies = new int[] {0, 2, 2, 2, 2};

            System.out.println(fizzers[fizzups[i % 3] + fizzies[i % 5]].fizz(i));
        }
    }
}

[flat gust]

you need two underscores for today's java + the three lambdas need to be changed

(for Arthur, since he's reading)

[alpine lantern]

I did not understand quite well these:

            var fizzups = new int[] {0, 1, 1};
            var fizzies = new int[] {0, 2, 2, 2, 2};

I know fizzups goes [0..2] because % 3 and I know fizzies goess [0..4] because % 5

But why the number 1 in the first arr and the number 2 in the second arr? Is it because we need to access the fizzers array (0..3)? How did you think about this?

fizzups[0] and fizzies[0] means that i is divisible by both 3 and 5. and "fizzbuzz" is at the first index of fizzers because of that, what I did not understand was:

Where did the 1's and 2's come from?

[viral quail]

yea, but java 21 👀

[alpine lantern]

my solution

With bg: