iOS repl.it - IF Else Challenge Solution

control_flow.swift

//Don't change this
var aYear =  Int(readLine()!)!

func isLeap(year: Int) {
    
    var leap = "NO"
    
    //IF divisible by 4 with no remainders.
    if year % 4 == 0 {
        leap = "YES"
        //Is leap year, unless:
    }
    if year % 100 == 0 {
        leap = "NO"
        //Is not leap year, unless:
    }
    if year % 400 == 0 {
        leap = "YES"
        //Is leap year.
    }
    
  
    
    print(leap)
    
    
}

//Don't change this
isLeap(year: aYear)

var aYear = 1904

func isLeap(year: Int) {
if aYear % 4 == 0 {
if aYear % 100 == 0 && aYear % 400 != 0 {
print("No")
} else {
print("Yes")
}
} else {
print("No")
}
}
isLeap(year: aYear)

Tried to shorten the code lines. But this did not work on playground.

var aYear =  Int(readLine()!)!

func isLeap(year: Int) {
  if year % 4 == 0 && year % 400 == 0 && year % 100 != 0 {
    print("Yes")
  } else {
    print("No")
  }
}

isLeap(year: aYear)

Here's the buildtime message:
error: Playground execution aborted: error: Execution was interrupted, reason: EXC_BREAKPOINT (code=1, subcode=0x18f6dd21c).
The process has been left at the point where it was interrupted, use "thread return -x" to return to the state before expression evaluation.

What could be wrong?

Who can explain what this line is for? Xcode gives an error on it

//Don't change this var aYear = Int(readLine()!)!

This is the request for an input, in this case the year to check for a leap year

var aYear = Int(readLine()!)!

func isLeap(year: Int) {
    if (year % 4 == 0 && year % 100 != 0) || year % 400 == 0 {
        print("\(year) is a leap year.")
    } else {
        print("\(year) is not a leap year.")
    }
}

isLeap(year: aYear)

it is not working for me.

What is the issue you are getting?

could someone please help me out here, i understand the steps necessary to get isLeap to say whether or not the year is a leap year but i cannot for the life of me understand the "==0" expression.

1. if year % 4 == 0 print yes, 2000 divided by 4 is 500 which is a whole number with no remainder but is not equal to zero
2. if year % 100 != 0 print no, 2000 divided by 100 is equal to 20 which again is not equal to zero but again is a whole number and finally 3. if year % 400 == 0 print yes 2000 divided by 400 is 5 which is a whole number but not equal to zero.

basically i wanna know what zero represents, is it an expression for a whole number?

So here the "==0" is calculate based on the modulus (remainder). Using the example 2000%4 which means that how many multiples of 4 will fit inside the value 2000 and returns the value that's left over which is 0 in this case.

More details check the screenshot below:
In the screenshot you can see at Line89 that the remainder of 2000%4 is 0 as there is no remainder.

If there is anything feel free to ask.
Thanks.

func isLeap(year: Int) {
    if year % 4 == 0 && (year % 100 != 0 || year % 400 == 0) {
        print("YES")
    }
    else{
        print("NO")
    }
}

var aYear = 2020

func isLeap(year: Int) {

    if year % 4 == 0 && year % 100 != 0 {
            print("Yes, Leap Year")
        } else if  year % 100 == 0 && year % 400 == 0 {
            print("Yes, A leap year")
        } else {
            print("No, Not a leap year")
        }

    }

isLeap(year: aYear)

Check my answer