Switch Statement: where Clause

Hi.
Right now I’m in Switch statements with where Clause.
In this exercise is an example:

ar randomNumber = Int.random(in: 0…10)

switch randomNumber {
case let x where x % 2 == 0:
print("(randomNumber) is even")
case let x where x % 2 == 1:
print("(randomNumber) is odd")
default:
print(“Invalid”)
}

What I don’t understand in this exercise is: why we use as divine symbol % and why there are this == at the end of both cases?

Hi - welcome back to the forums!

Let’s look at one of the case statements from your code block, and break it down. We’ll use this line:

case let x where x % 2 == 0:

  • case - we know the case keyword defines a possible scenario that our switch is designed to handle.

  • let x - here we are doing what Swift refers to as “value binding”; we are using a temporary variable (x) to hold the value we are considering in this case.

  • where x % 2 == 0 - in a case statement, where allows you to expand the situations to which the case applies. Here we are only interested in values of x where we can divide it by 2 and have a 0 remainder. (We are using the remainder % operator, which you can read more about here.)

So, our first case - case let x where x % 2 == 0: - deals with values of randomNumber which are even. We are taking randomNumber, putting it temporarily into the variable x, and then checking that its remainder (the % operator) is equal to 0 by using the equality (“equal to”) operator ==.

Similarly, in our second case - case let x where x % 2 == 1: - we are taking randomNumber and putting it temporarily into the variable x, then checking to see if its remainder is 1.

Does that help at all? :slight_smile: