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The question is very simple, but I just could not find the answer!
Why doesn't
return x == 0? "" : "Hello"
compile but
return x == 0 ? "" : "Hello"
does?
This is really weird because all the other operators don't need an extra white space. e.g.
let x = 1+1
let y = 1 + 1
are the same.
I think it has something to do with optionals. But when you use a ? operator on a variable, it must be used like this:
let s: String? = nil
let x = s?.startIndex
I mean it must follow another operator, right?
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Emphasis: value-selection before/after action needing values. There's a different emphasis: An if / else statement emphasises the branching first and what's to be done is secondary, while a ternary operator emphasises what's to be done over the selection of the values to do it with.
The ternary operator take three arguments: The first is a comparison argument. The second is the result upon a true comparison. The third is the result upon a false comparison.
Moreover, as has been pointed out, at the byte code level there's really no difference between the ternary operator and if-then-else.
Advantages of Ternary OperatorIt will shorten the code. It will improve the readability of the code. The code becomes more straightforward. Makes basic if/else logic easier to code.
I think it has something to do with optionals.
It does. The documentation on operators says:
There is one caveat to the rules [regarding whitespace around operators]. If the
!or?predefined operator has no whitespace on the left, it is treated as a postfix operator, regardless of whether it has whitespace on the right. To use the?as the optional-chaining operator, it must not have whitespace on the left. To use it in the ternary conditional (?:) operator, it must have whitespace around both sides.
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