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iOS Swift Basics (retired) Control Flow While and Do-While Loop

Posted by Marquett Burton
Marquett Burton
511 Points

while index < numbers.count { --Why does the first line print as 0 is not less than 0?

It seems that this piece of code relies on the idea that 0 is less than 0 when they are equivalent. Correct?

while_loops.swift 
let numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
William Li
William Li
Courses Plus Student 26,868 Points
William Li
William Li
Courses Plus Student 26,868 Points

I don't quite get what your question is, can you elaborate ?

John Magee
John Magee
Courses Plus Student 9,058 Points

numbers.count is not 0 - numbers.count is a count of the number of elements in the aray, 10? I don't know why you think 0 is comparing to 0

kjvswift93
kjvswift93
13,515 Points

var index = 0 is simply setting 0 as the initial value for this variable named index, which will be used within the println statements. With the while loop in place followed by "index++", index will no longer be 0 when it sees that there is an element inside of the array. Since there is an element inside of the array (the number 1) that means the println function must be called because one is greater than 0. Index is now = 1, so it prints "1". Then, since it sees another element after the first one, index must then = 2 so as to print out "2". Index never stops doing this until there are no more elements left in the array.

1 Answer

kjvswift93
kjvswift93
13,515 Points
kjvswift93
kjvswift93
13,515 Points

I think that I can help explain it so that you will understand what is going on here a little better. First, I'll show you what the correct answer looks like below:

let numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
var index = 0   

while index < numbers.count {  
  println (numbers[index])
  index++
}

I used a variable named index and assigned it to the Int value 0. Essentially the next line beginning with the word 'while' states "as long as the number of elements in the numbers array are greater than 0, then print out each element in the array until reaching the last element in the array, in which case there are no more elements left."