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iOS Swift 2.0 Collections and Control Flow Control Flow With Conditional Statements Logical Operators

Brian Patterson
Brian Patterson
19,588 Points
Posted by Brian Patterson
Brian Patterson
19,588 Points

Don't know how to get a multiple of 7 for the challenge.

var results: [Int] = []

for n in 1...100 {
    // Enter your code below
    if n / 2 != 0 && 7 / 100 == 0 {

        results.append(n)
    }

    // End code
}

6 Answers

Steve Hunter
Steve Hunter
57,712 Points

Hi Brian,

As above, the mod operator gives you an indication that something is divisible by another number. The same approach can be adopted to test for "oddness" or "evenness", but by using the figure 2.

There's another post on that challenge here that covers off the detail for you.

I hope it helps.

Steve.

Michael De La Cruz
Michael De La Cruz
10,800 Points
Michael De La Cruz
Michael De La Cruz
10,800 Points

This makes sense and all but % was not explained in the videos. Why make that the answer to the question? I figured it out myself how to do it but that is only because I have prior experience of coding.

Luke Pettway
Luke Pettway
16,593 Points
Luke Pettway
Luke Pettway
16,593 Points

Try using modulus: %

n % 7 == 0

If the number modulus 7 is zero then it is divisible by 7.

Brian Patterson
Brian Patterson
19,588 Points
Brian Patterson
Brian Patterson
19,588 Points

Thank you Steve and Luke. It all makes sense now! I was close, but did not have the right operator.

Paul Je
Paul Je
4,435 Points
Paul Je
Paul Je
4,435 Points

why is it == and not =?

Steve Hunter
Steve Hunter
57,712 Points

Hi Paul,

Double-equals is the comparison operator, so it compares the equality of the two things either side of it and returns true or false depending on whether they are equal or not.

Single equals is an assignment operator, which assigns the value to the right of the equals sign into the variable to the left.

Make sense?

Steve.

joshua86
joshua86
5,013 Points
joshua86
joshua86
5,013 Points

This one took me forever.

var results: [Int] = []

for n in 1...100 {

if n % 2 != 0 && n % 7 == 0

{ results.append(n) }

}

Paul Je
Paul Je
4,435 Points
Paul Je
Paul Je
4,435 Points

Okay, thank you for that - could you also clarify why the left side of the && doesn't necessarily require a T/F, whereas the right side of the && requires a ==? I tried to equal the n % 7 to 0, but then the answer was wrong. Is this technically possible and right? Or just entirely wrong on my end?

Steve Hunter
Steve Hunter
57,712 Points

An && just needs to be able of comparison - do you have an example to illustrate your point?

Take n % 3 && n % 7 for example. If both mod operators evaluate to the same thing, the && returns a true.

So, 

var a = 12 % 6 // 0
var b = 4 % 2 // 0
var equal = a == b // 0 == 0 -> true

var a = 11 % 6 // 5
var b = 4 % 2 // 0
var equal = a == b // 5 == 0 -> false