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

Aaron Clayton
Aaron Clayton
325 Points

Sum of array

The second task is never covered in videos. I am lost.

I don't even know where to start.

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++ 
}

1 Answer

Chris Shaw
Chris Shaw
26,662 Points

Hi Aaron,

Getting the sum total of the array is very straight forward, the expectation is however that you would have learned this from previous Swift courses which explain basic operators such as sum.

You can learn more about operators in the Swift Basics course.

In the case of task 2 of this challenge, we need to use the addition + operator or the shorthand += operator. Both of these operators allows us to add a new value to an existing value.

Using the basic addition operator +

let number = 1
number = number + 1

Using the shorthand addition operator +=

let number = 1
number += 1

In the case of this challenge, we need to get the total of all the numbers in the numbers array. As we have a counter variable which we're incrementing the total of; we can use it to access each index within our array and then add the value to our sum variable.

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

Alternatively, we can also use the shorthand operator for addition which yields the same result as above.

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

Hope that helps!