CODEWITHSUNDEEP
c#arrays
user995689
user995689

Reputation: 825

Multiply elements in an array

Hi, I have an array : int [] num = new int[6]{1,2,2,1,1,2};

I want to multiply the value at element 0 with every other value, I then want to multiply the value at element 1 with the values at elements 2 through to the last element. Then multiply the value at element 2 with the values from 3 through to the end, and so on until I have iterated through the whole array.

My efforts thus far seem clumsy and verbose, so I was wondering if anyone could show me an elegant way of achieving my aim.

Many thanks.

Upvotes: 3

Views: 6984

Answers (4)

demo.b
demo.b

Reputation: 3439

int[] num = new int[6] { 1, 2, 2, 1, 1, 2 };

        int i = 0;

        while (i < num.Length)

        {
            for (int j = i; j < num.Length;j++)

            {

                if((j+1)<num.Length)

                num[i] = num[i] + num[j + 1];

            }

            Console.WriteLine(num[i]);

            i++;

        }

Upvotes: 0

Ray
Ray

Reputation: 46555

You can go through the array backwards and do it in one pass and not repeat operations.

 for (int i = num.Length - 2; i >= 0; i--)
 {
     num[i] *= num[i + 1];
 }

Gives 8,8,4,2,2,2

Upvotes: 8

spender
spender

Reputation: 120380

Enumerable.Range(0,num.Length)
    .Select(i => num.Skip(i).Aggregate(1, (a, b) => a * b))

Gives a sequence 8, 8, 4, 2, 2, 2. Is this what you meant?

Upvotes: 2

Roy Dictus
Roy Dictus

Reputation: 33139

This should do the job:

for (int i = 0; i < num.Length; i++)
{
    // Multiply element i
    for (int j = i+1; j < num.Length; j++)
    {
       num[i] *= num[j];
    }
}

Upvotes: 1

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