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# Stuck in a code challenge (again)...

Hi there!

I'm stuck yet again to the same topic but different code challenge:

https://teamtreehouse.com/library/swift-3-collections-and-control-flow/control-flow-with-loops/working-with-loops

I got the first task right. I set the while loop up. Which is:

while counter < numbers.count { counter += 1 }

But task 2 is pretty difficult (for a beginner like me). How do I compute for the sum of all of the values in the array? I understand the question, I just can't seem to translate it into code.

Hi!

Here's the correct code and explanation.

let numbers = [2,8,1,16,4,3,9] var sum = 0 var counter = 0

while counter < numbers.count { sum += numbers[counter]
counter += 1 }

So here, we have the variable counter which increments by the value 1 (counter+= 1). As the while loop moves further and performs the task, counters value increases by 1.

The counter works as the index position in the array numbers. For example array[3], here 3 is the index position and retrieves the value from the position.

Like, the index position 0 in our array numbers has the value of 2.

The sum is calculated by sum = sum + numbers[counter] where initially the sum is 0. So if you form a data table..

counter numbers[counter] sum

//0 is the initial value of sum + numbers[0] is 2 and then the value is stored in sum.

0 2 0+2 = 2
1 8 2+8 = 10 2 1 10+1 = 11 //0 is the initial value of sum + numbers[counter] is 2 and then stored in Sum. and so on... I would suggest you form such data tables. They're very useful.

Thanks man! Appreciate the help. This is very useful indeed!