coding question C#,JAVA,CPP

[Liam mallka]

I got this code in a test where I can use friends, the internet, etc... and I need to explain what problem this code solves, however I cant figure it out

the output that I got is 1 2 3 5 7 11 12 but I cant connect the numbers.

N=15

 

[minibois]

The clue is in the "for(i=2..." loop, or more specifically the "for (j=i+1.." loop. 

It sets certain numbers in the array 'a' to zero, as to not print them out at the end.

 

What is something the numbers you mentioned have in common why they do pass this modulo (%) if-statement? 

Go by each number (1-15), write the value of i and j in these loops and check why some pass and others don't pass this test (doublecheck what the modulo statement does if you're not sure what it's checking).

[heimdali]

50 minutes ago, Liam mallka said:

what problem this code solves

What makes you think it solves a problem?  What it does is it creates a problem unless you ignore it.

 

 

[Guest]

This is a standard math thing, but let's not Google it. 

 

Look at the numbers at the beginning. 

i and j are whole numbers as they are integers. 

 

We also have an array which wasn't declared but we know the array is called a. 

The first for loop sets the values of a to what?

List that out. 

 

Something to pay attention to is that there is only one i and one j. 

Where are the values for these variables changed? 

Circle them and post a picture. 

Write out on paper every time the array a is changed and what every value is. 

 

Go through the program by hand with a piece of paper and a pen. 

 

Doing this, you'll understand how they relate. 

If you can power through this the hard way, you'll be much better for it. 

[james__5]

EDITED. If only there was number sequence that cannot by divided by any other number.

[Eigenvektor]

9 hours ago, Liam mallka said:

the output that I got is 1 2 3 5 7 11 12 but I cant connect the numbers.

N=15

Then you did something wrong, it should print 1, 2, 3, 5, 7, 11, 13.

 

Technically 1 should not be in there either.

[Guest]

2 hours ago, james__5 said:

Primes. It prints prime numbers.

Don't give him the answer. Help him come to the conclusion. 

[Guest]

2 hours ago, Sakuriru said:

Correct answer is a compiler error because the array a has never been declared or initialized.

Amongst other poor coding conventions lol

[Eigenvektor]

On 11/18/2022 at 10:49 PM, Sakuriru said:

True, so it doesn't print the prime numbers.

 

What a freakin mess.

Here's a modern adaption of the algorithm that produces the expected values

final int n = 17;
IntStream.rangeClosed(2, n)
    .filter(i -> IntStream.range(2, i).noneMatch(j -> i % j == 0))
    .forEach(System.out::println);

 

[Vicarian]

On 11/18/2022 at 6:14 AM, Liam mallka said:

I got this code in a test where I can use friends, the internet, etc... and I need to explain what problem this code solves, however I cant figure it out

the output that I got is 1 2 3 5 7 11 12 but I cant connect the numbers.

N=15

 

I know this is super late, but in case anyone else stumbles across this mess, there's a blatant syntax error in the conditional for the last loop, on top of the compiler error for the array a neither being declared nor initialized.  As far as I'm aware,

-<=

isn't an operator, but maybe my Java is rusty.  Whoever wrote this question needed to not use Word or whatever other rich text editor to write it.  I seriously hope that wasn't the answer the exam administrator was looking for.  I hate trick questions.

[heimdali]

For all I know whoever asks such a question has a problem with a lack of intelligence, and if the code solves it for them is only for them to decide.