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Anjali Pasupathy
2,017 PointsWhy do if case statements use the assignment symbol rather than the equality symbol?
The example given used the syntax,
if case .Nickel = coin { print("Statement") }
Why does if case syntax use = rather than ==?
2 Answers
Greg Kaleka
39,021 PointsSort of. case .Nickel returns a boolean, when checking the value of coin. Just like in a switch statement.
It's identical to:
switch coin {
case .Nickel:
print("Statement")
default:
break
}
It's just a lot cleaner to write.
if case .Nickel = coin { print("Statement") }
Nathan Tallack
22,160 PointsAh, so case works as a boolean evaluator not the =. Got it. :)
Greg Kaleka
39,021 PointsHi Anjali,
So this is a little tricky to explain, because it's sort of syntactical sugar, as Pasan mentions. The equal sign is not a comparison operator here. Instead, it's telling the compiler what .Nickel is a case of. Put another way, it's telling the compiler what we're switching on.
The check is "If the case is a .Nickel". You can sort of think about a double equals between case and .Nickel. This is the same way you might think about a switch statement. Here, though, we're not in a switch statement, so we have to tell the compiler what to check the case of, hence the = coin. We're not checking to see if it's a coin - we know it's a coin!
Anyway, like I said this is a tricky concept - I do wish Pasan had spent a bit more time explaining it. Let me know if this makes sense!
Cheers,
Greg
Nathan Tallack
22,160 PointsSo in this case .Nickel = coin returns a boolean? How can that be? It would need to be a boolean to be a conditional qualifer right?
Nathan Tallack
22,160 PointsNathan Tallack
22,160 PointsI would love to know the answer to this also!