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

I need help

I don't understand this

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}

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

}

2 Answers

tromben98
tromben98
13,273 Points

Hi here is the solution:

Using the value of counter as an index value, retrieve each value from the array and add it to the value of sum.

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

// Enter your code below

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

You want to increment counter last. On the first time through counter is 0 so 2 is added to sum and then counter is incremented and becomes 1. Then on the second pass through 8 is added to sum giving sum the total of 10 and so on. This is because counter is equal to 1 and the number 8 is in the 1 spot in the numbers array.

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

// Enter your code below
while counter < numbers.count {
  sum = sum + numbers[counter]
  counter += 1
}