Welcome to the Treehouse Community

Want to collaborate on code errors? Have bugs you need feedback on? Looking for an extra set of eyes on your latest project? Get support with fellow developers, designers, and programmers of all backgrounds and skill levels here with the Treehouse Community! While you're at it, check out some resources Treehouse students have shared here.

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and join thousands of Treehouse students and alumni in the community today.

Start your free trial

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

Posted by Francis Williams
Francis Williams
678 Points

keep getting this error " ++ is unavailable: it has been removed from swift 3

while(counter < numbers.count){ sum += numbers[counter] counter++

keep getting the error "++ is unavailable

loops.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 += 1
   sum += numbers[counter]
   counter++
}

2 Answers

wwyattw
wwyattw
10,389 Points
wwyattw
wwyattw
10,389 Points

I wondered about the same also but then I found this, https://stackoverflow.com/questions/35158422/the-and-operators-have-been-deprecated-xcode-7-3

andren
andren
28,558 Points
andren
andren
28,558 Points

That message is accurate. The ++ operator was removed in Swift 3, and since you use it in the last line of your loop your code won't run. You don't really need that line though as you are already increment counter with += 1 at the top of the loop which is a valid way of increment in Swift 3.

You shouldn't increment it at the start of the loop though, but at the end, since counter is used to pull items out of the numbers array.

If you remove your last line and move the first line down like this:

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

Then your code will work perfectly fine.