CODEWITHSUNDEEP
java
CALVIN
CALVIN

Reputation: 29

Arraylist length, I dont think my teacher is correct about this

We were told to find the value of a[1] after executing the following program:

int [] a = {0,1,2,3,4} ;
for(p=0 ; p< a.length ; p++){
    a[p] = a[ (p + 3) % a.length] ;
}

So my teacher work it out like this

a[0] = a[(0+3) % 4]; = 3
a[1] = a[(1+3) % 4]; = 0

So a[1] = a[0] therefore a[1] = 3

But I think the a.length should be 5 so a[1] = a[(1+3) % 5]; = 4

What is the correct answer?

Upvotes: 3

Views: 90

Answers (2)

tryingToLearn
tryingToLearn

Reputation: 11659

Yes you are partially right.

Length will be 5.

But if you work your way up, you would see that 

a[0] = a[(0+3) % 5] ===> a[3] = 3;
a[1] = a[(1+3) % 5] ===> a[4] = 4;
a[2] = a[(2+3) % 5] ===> a[0] = 3; // note that now a[2] will take updated value of a[0];

& so on

Upvotes: 4

Martin B.
Martin B.

Reputation: 1663

You are right:
a.length is the number of elements in the array. There are 5 elements: 0,1,2,3,4.

Therefore A[1] = a[(1+3) % 5]; = 4

Further expanding on .length:
When you access a[a.length] you are out of bounds. This is why you have p < a.length in your for-contidion. The indices are 0-indexed meaning the 1st element has index 0. But non-the-less; if there is only a[0] present, there is 1 element.

Upvotes: 1

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