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c#arraysfor-loopforeach
superuser
superuser

Reputation: 455

How to skip every 3rd element from the array?

I am trying to write a simple logic. Based on this logic I should implement my actual logic in project.

so far I have tried the below code.

int[] num = new int[11];

for (int i = 1; i < 6; i++)
{
    num[2 * (i - 1) + 1] = i;
}

foreach (var item in num)
{
    Console.Write(item + " ");
}

The output is - 0 1 0 2 0 3 0 4 0 5 0

But I want the output as in this 0 1 2 3 0 4 5 6 0 7 8 9 0 format.

What should be write in this code - num[2 * (i - 1) + 1]

Upvotes: 0

Views: 2016

Answers (3)

Maarten
Maarten

Reputation: 22955

To get the return you want, try this:

var num = new int[12];
for (int i = 1; i < 10; i++) {
    num[i + ((i - 1) / 3)] = i;
}

This yields: 0 1 2 3 0 4 5 6 0 7 8 9.

The logic behind it is that you need to add an extra 1 to the calculated index for every set of 3. The - 1 is to shift the set-of-three to the required position.

Update

To remove the first 0 you have to subtract 1 from the calculated index.

var num = new int[11];
for (int i = 1; i < 10; i++) {
    num[i - 1 + ((i - 1) / 3)] = i;
}

This yields: 1 2 3 0 4 5 6 0 7 8 9

Upvotes: 3

Prasanth V J
Prasanth V J

Reputation: 1196

        int[] num = new int[11];
        int j = 0;
        for (int i = 1; i < 10; i++)
        {

            if (i%4 != 0)
            {
                num[i] = i - j;
            }
            else
            {
                j= j + 1;
            }

        }

        foreach (var item in num)
        {
            Console.Write(item + " ");
        }
        Console.Read();

Upvotes: 0

PermaFrost
PermaFrost

Reputation: 1446

I don't quite follow how skipping every 3rd element is going to yield the result you mentioned. But you need to figure out a way to identify each "3rd element" by looking at the index; this is commonly done using the MOD operator (% for C#, check the internet for "modulo operation") and then checking the result, index % 2 == 0 would be true for every even value of index or "every 2nd value" if the index values are continouous.

The rest should be easy to figure out I guess.

Upvotes: 0

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