Switch statement in Swift

Question

I'm learning syntax of Swift and wonder, why the following code isn't working as I expect it to:

for i in 1...100{      switch (i){     case 1:         Int(i%3) == 0         println("Fizz")     case 2:         Int(i%5) == 0         println("Buzz")     default:         println("\(i)")     }   } 

I want to print Fizz every time number is divisible by 3 (3, 6, 9, 12, etc) and print Buzz every time it's divisible by 5. What piece of the puzzle is missing?

Note: I did solve it using the following:

for ( var i = 0; i < 101; i++){      if (Int(i%3) == 0){         println("Fizz")     }   else if (Int(i%5) == 0){         println("Buzz")     }   else {         println("\(i)")     }    } 

I want to know how to solve this using Switch. Thank you.

Answer 1

The usual rules for the FizzBuzz game are to replace every multiple of 3 by "Fizz", every multiple of 5 by "Buzz", and every multiple of both 3 and 5 by "FizzBuzz".

This can be done with a switch statement on the tuple (i % 3, i % 5). Note that _ means "any value":

for i in 1 ... 100 {     switch (i % 3, i % 5) {     case (0, 0):         print("FizzBuzz")     case (0, _):         print("Fizz")     case (_, 0):         print("Buzz")     default:         print(i)     } } 

Answer 2

Switch statements in Swift support value bindings.
This allows you to assign a value that matches a certain condition (evaluated via the where clause) to a temporary variable (x & y here):

for i in 1...100 {     switch (i){     case let x where x%3 == 0:         println("Fizz")     case let y where y%5 == 0:         println("Buzz")     default:         println("\(i)")     } } 

You could also use the assigned temp value in the case body.

Update:
Matt Gibson points out in the comments, that you can omit the assignment to a temp var if you are not going to use it in the case body.
So a more concise version of the above code would be:

for i in 1...100 {     switch (i){     case _ where i%3 == 0:         println("Fizz")     case _ where i%5 == 0:         println("Buzz")     default:         println("\(i)")     } } 

Side note: Your 2 code samples are slightly different (the first one uses the range 0-100 as input, while the second one operates on 1-100). My sample is based on your first code snippet.