FAQ: Arrays: Lesson - Looping Through Arrays

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1

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This community-built FAQ covers the “Looping Through Arrays” exercise from the lesson “Arrays: Lesson”.

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FAQs on the exercise Looping Through Arrays

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2

Guys can you help me to resolve the 2nd part of this problem?

Given the integer array arr2 , fill up the array so that each element in the array is four plus the index of the element.

Example:

arr[0] = 4 , arr[1] = 5 , arr[2] = 6 , etc.

3

That phrasing, “four plus the index” is important. How might you translate that to code?

1 Like
4

So far i get;

#include<stdio.h> int main() { int arr[] = {3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 20, 22, 26, 28, 29}; int arr2[100]; int i = 0, aux = 1; // Code for Checkpoint 1 goes here for (i = 0; i < 20; i++){ printf("%d\n", arr[i]); } // Code for Checkpoint 2 goes here arr2[0] = 4; printf("%d\n", arr2[0]); for (i = 1; i < 100; i++){ arr2[i] = arr2[0] + aux; printf("%d\n", arr2[i]); aux++; } }
1 Like
5

Hi romanopaulo708735117,

i got to this awmser and i do think that should be right, anyway you should try.

#include<stdio.h>

int main() {
  int arr[] = {3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 20, 22, 26, 28, 29};
  int arr2[100];
    for(int j = 0; j < 100; j++)
    {
      arr2[j] = j + 4; 
      printf("%i\n", arr2[j]);
    }
}

let me know if helped

6

So I’ve solve this 2nd problem task, and I can access the array elements using printf() but only using the negative indices, if I use positive indices, I keep getting 5, can anyone explain why this is the behavior?
image
This above is my soultion with the added printf() giving me just rows of 100 '5’s.

7

You have 100 “5” because you assigned 100 times “4+1”.
You should try to use the current index of the array and add 1 to it.

1 Like
8

I’m on the first part of this exercise and I cannot figure out how to make it stop looping. Please let me know what I’m doing wrong!

const vacationSpots = [‘Bali’, ‘Paris’, ‘Tulum’];

// Write your code below

for (let i = 0; i < vacationSpots.length; i++){

console.log('I would love to visit ’ + vacationSpots[i = 0]);

}

9

I think you posted in the wrong thread. This is a thread about arrays in C, whereas your question is about arrays in JavaScript. Specifically, you are talking about the exercise: Looping through Arrays
The C and JavaScript exercise both have the same title “Looping through Arrays”, so the misunderstanding is understandable.

The problem is in your console statement:

console.log('I would love to visit ' + vacationSpots[i = 0]);

In the first iteration of the loop, i starts off as 0 because of let i = 0;

When you do vacationsSpots[i = 0], you are assigning 0 to i and then printing the element at index 0 in the vacationSpots array i.e. you are printing the string "I would love to visit Bali"

After the console statement, you finish the iteration. The for loop increments i to 1 and the next iteration of the loop begins. When you get to vacationsSpots[i = 0] in the console statement, you once again reset i to 0. The "I would love to visit Bali" string is printed. The iteration finishes. The loop increments i to 1 and the next iteration begins. You are caught in an endless cycle i.e. an infinite loop. You keep resetting i to ‘0’ in the console statement.

Instead, the correct statement should be:

console.log('I would love to visit ' + vacationSpots[i]);

Now, in the for loop, i will have value of 0 in first iteration, 1 in second iteration and 2 in third iteration. When i becomes equal to vacationSpots.length (which is 3 in this case), then the loop finishes.

10

WARNING- ANSWERS TO QUESTION 2
I was able to get my green checkmark with the following code:

int j = 0;

while(j < 100)
{
  arr2[j] = 4 + j;
  printf("%i\n", arr2[j]);
  j++;
}

You can also do it with a for loop. I’ll put that up here too:

for (int j = 0; j < 100; j++)
{
arr2[j] = j + 4;
printf(“%i\n”, arr2[j]);
}

I tested both of these codes out myself and they both got me the green checkmark. Hope this helps.