Swift Tutorial Part 3: Flow Control | raywenderlich.com

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Welcome to part 3 of our Swift tutorial, where you’ll learn how code decisions using Booleans and repeat tasks using loops to control the flow.

This is a companion discussion topic for the original entry at https://www.raywenderlich.com/6366-swift-tutorial-part-3-flow-control
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lorenzo you need to explain better as i cannnoot understand and i is 8

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Hi Thomas, could you tell me which part / code snippet is not clear?

Thanks, Lorenzo

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hi again borat, this just as confusing as the other one

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@anthonybigdawg Please let me know what don’t you understand exactly when you get a chance. Thank you!

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count = 10
sum = 1
var lastSum = 0

for _ in 0…<count {
let temp = sum
sum = sum + lastSum
lastSum = temp
}

This code will iterate 10 times (from 0 to 9)
But what is the code doing, exactly?

The variable ‘sum’ starts at ‘1’ and the range starts at ‘0’. This is what I’m getting:

sum = 1 + 0
sum = 1 + 1
sum = 2 + 2
sum = 4 + 3
sum = 7 + 4
sum = 11 + 5
sum = 16 + 6
sum = 22 + 7
sum = 29 + 8
sum = 37 + 9

I know it’s wrong, because the result gives 55. Can you please explain the above code in words?

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@triplespace You can get the sum of all digits with the following code snippet:

var sum = 0
for digit in 1...9 {
  sum += digit
}

Please let me know if you have any questions or issues about the whole thing.

Thank you!

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Thank you. I can understand the code you provided, it’s much more straightforward.

I just want to make sure I’m not missing anything with the other code. Trying to get the basics down.

What is the other code saying?

“In the range 0 to 9, the constant ‘temp’ = ‘sum.’
‘sum’ = its own value + ‘lastSum.’
‘lastSum’ = ‘temp’”

The first iteration is?
temp = 1
sum = 1 + lastSum
lastSum = 1

temp = ??

I think the order is confusing me.

Thanks for your help.

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This tutorial is more than six months old so questions are no longer supported at the moment for it. Thank you!