Welcome to the Treehouse Community

The Treehouse Community is a meeting place for developers, designers, and programmers of all backgrounds and skill levels to get support. Collaborate here on code errors or bugs that you need feedback on, or asking for an extra set of eyes on your latest project. Join thousands of Treehouse students and alumni in the community today. (Note: Only Treehouse students can comment or ask questions, but non-students are welcome to browse our conversations.)

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and a supportive community. Start your free trial today.

iOS Swift 2.0 Collections and Control Flow Control Flow With Loops Working with Loops

Amy Nicholson
Amy Nicholson
783 Points
Posted by Amy Nicholson
Amy Nicholson
783 Points

Stuck, Swift Collections Control Flow

Task 2 of 2 asks: Now that we have the while loop set up, it's time to compute the sum! Using the value of counter as an index value, retrieve each value from the array and add it to the value of sum.

For example: sum = sum + newValue. Or you could use the compound addition operator sum += newValue where newValue is the value retrieved from the array.

I have this (for task 1 of this challenge):

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

But cannot figure out task 2. Thank you!

while.swift 
let numbers = [2,8,1,16,4,3,9]
var sum = 0
var counter = 0
// Enter your code below

while counter < numbers.count{

    counter++
}

3 Answers

Ryan Huber
Ryan Huber
13,021 Points

There are a couple of ways to do this. Let's walk through this in code

let numbers = [2,8,1,16,4,3,9]
var sum = 0
var counter = 0
// Enter your code below

while counter < numbers.count{
  // inside the loop we need to add the number from our array
  // during each iteration to the sum
  // let's first get the number from our array
  var newValue = numbers[counter] // this will assign the value from the array at an incrementing index based on counter
  // next let's add that value to out running total for sum
  sum += newValue
  // then we increment the counter
  counter++
}

Let me know if you have any other questions about this challenge.

Amy Nicholson
Amy Nicholson
783 Points
Amy Nicholson
Amy Nicholson
783 Points

Thank you Ryan - that works. I am so confused by the brackets and dots and parens ... when to use which, and other confusion too. But I will carry on! Amy

Ryan Huber
Ryan Huber
13,021 Points
Ryan Huber
Ryan Huber
13,021 Points

There is a lot to the syntax, especially if you are new to programming. Feel free to reach out if you have any questions. I try to answer things with commented code because it makes sense to me that way. Good luck in your learning!

Amy Nicholson
Amy Nicholson
783 Points
Amy Nicholson
Amy Nicholson
783 Points

Thank you Ryan! (Yes, I am new to programming. I'm hoping that a lot of the syntax will become second nature soon enough.)