C#•3y ago

✅ Need help with an if statement

I'm essentially trying to write an if statement where the code executes only if the list named "list" contains only the variables n and the number 1

Moods•7/9/23, 9:09 PM

Does that run??? If the user entered a number bigger than 2 the condition checks for mod 0

Moods•7/9/23, 9:10 PM

Also Convert.ToInt32 isn’t really good

JakenVeina•7/9/23, 9:10 PM

why not?

Moods•7/9/23, 9:10 PM

I could enter abc

JakenVeina•7/9/23, 9:10 PM

oh, right, it's the string version

JakenVeina•7/9/23, 9:10 PM

yeah, you want Int32.TryParse()Int32.TryParse()

Original message was deleted

AceChewyOP•7/9/23, 9:28 PM

I'm not sure how to make an if statement where it executes when only two specific values are found within the list

AceChewyOP•7/9/23, 9:28 PM

a value in the lsit equal to 1 and another equal to number

MMoods Also Convert.ToInt32 isn’t really good

AceChewyOP•7/9/23, 9:29 PM

Oh ok, thanks for the heads up

AceChewyOP•7/9/23, 9:30 PM

what would the function for that last bit be?

Moods•7/9/23, 9:30 PM

Why are you checking if the count is equal to 2 :o

Moods•7/9/23, 9:31 PM

Also is this like a function to find all the prime numbers up to a given input?

AceChewyOP•7/9/23, 9:31 PM

More so to check if a number is prime

Moods•7/9/23, 9:32 PM

If I entered 2, and I’m reading this correctly, it would check if 2 modulo 0 was equal to 0?

AceChewyOP•7/9/23, 9:32 PM

I'm doing it quite inefficiently but essentially, I only want to store the value of i ( the factor) if the remainder is 0 and a priem numbers factor is itself or one, it means if i store them in an array, I can check whether that's true and return an output

MMoods If I entered 2, and I’m reading this correctly, it would check if 2 modulo 0 was...

AceChewyOP•7/9/23, 9:33 PM

I thought the % was checking for a remainder

Moods•7/9/23, 9:33 PM

Which it does by dividing no?

Moods•7/9/23, 9:33 PM

I may be wrong though

MODiX•7/9/23, 9:34 PM

calledude

REPL Result: Success

0 % 2

0 % 2

Result: int

Compile: 265.411ms | Execution: 21.731ms | React with ❌ to remove this embed.

Moods•7/9/23, 9:34 PM

The 0 is on the right hand side

Moods•7/9/23, 9:35 PM

Also yeah I could have used modix to check (but idk how to use the bot)

Moods•7/9/23, 9:36 PM

Ok yeah in the first loop iteration unless number was less than 2 it’d always check for number % i

Moods•7/9/23, 9:36 PM

And i happens to be 0 then

AceChewyOP•7/9/23, 9:37 PM

Yh, I just added that piece of code since you can't get a prime number below 2

Moods•7/9/23, 9:39 PM

Wouldn’t the easiest way be, to loop from 2 to half(floor) the input, then running mod on the input with each i to see if it’s prime

AceChewyOP•7/9/23, 9:41 PM

Oh yh, that would work - let me try that real quick

AceChewyOP•7/9/23, 9:48 PM

Right, so I've rearranged some parts now (still not complete

AceChewyOP•7/9/23, 9:48 PM

How do I ensure that the else branch does nothing and just moves onto the next count of x

Moods•7/9/23, 9:49 PM

~~by not having it~~

Moods•7/9/23, 9:49 PM

Also what is the list doing there

AceChewyOP•7/9/23, 9:50 PM

So initally I simply wanted to check if a number is prime and so the list would store the number and the value 1 to show that a number is prime

Moods•7/9/23, 9:50 PM

Ohhhhh

AceChewyOP•7/9/23, 9:50 PM

However, I had forgotten that I wanted to return the prime factors, so now it stores those

AceChewyOP•7/9/23, 9:51 PM

I've made a mess of the explanation so sorry about that

AceChewyOP•7/9/23, 9:51 PM

Probably could have added some comments

Moods•7/9/23, 9:51 PM

Now I’m just curious as to why there’s a loop inside a loop

Moods•7/9/23, 9:51 PM

You can just have one loop

AceChewyOP•7/9/23, 9:51 PM

Wait, the first loop is redundant

AceChewyOP•7/9/23, 9:58 PM

Ok, I've streamlined some things but now I'm getting a divide by 0 error

Moods•7/9/23, 9:59 PM

Yeah that would be what I said earlier

MODiX•7/9/23, 9:59 PM

calledude

REPL Result: Failure

5 % 0

5 % 0

Exception: CompilationErrorException

- Division by constant zero

- Division by constant zero

Compile: 281.084ms | Execution: 0.000ms | React with ❌ to remove this embed.

Moods•7/9/23, 9:59 PM

X doesn’t start from 0

Moods•7/9/23, 10:02 PM

No I mean

Moods•7/9/23, 10:02 PM

It shouldn’t

Moods•7/9/23, 10:02 PM

If you’re testing for prime stuff

Moods•7/9/23, 10:02 PM

You start with 2

Moods•7/9/23, 10:02 PM

You divide, starting from 2 to half the number

AceChewyOP•7/9/23, 10:03 PM

so should the for(int x =0; x<= number/2; x++)

AceChewyOP•7/9/23, 10:03 PM

be for(int x = 2; .....) instead

Moods•7/9/23, 10:05 PM

I just remembered you’re adding these things to a list, it starts from 1 then not 2 :)

✅ Need help with an if statement

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