CODEWITHSUNDEEP
swiftxcodeoperators
Bug-Gy
Bug-Gy

Reputation: 61

Problem with NOT operator in Swift clauses

I'm programming in Swift 5.0 an app to move my character around a world and I've some problems with the NOT (!) operator in the if condition body. I wrote:

 if character.!isBlocked {
    character.moveForward()
 }

but the compiler say: Error: ".!" it's not a binary operator

Instead, if I wrote 

if character.isBlocked {
        character.turnBack()
     }

it works perfectly. Its possible to use a negative clause as if condition clause?

Upvotes: 1

Views: 171

Answers (1)

Ahmad F
Ahmad F

Reputation: 31645

If you are aiming to validate as "if not", then you should implement it as:

if !character.isBlocked {
    character.moveForward()
}

The logical NOT ! operator is a unary prefix operator:

  • Unary: it is for a single target.

  • Prefix: it should be before the target.

So, why it should be before character.isBlocked but not isBlocked?

Because character.isBlocked is the boolean to evaluate, isBlocked is the property name. The correct syntax is to use ! to evaluate the whole thing (Boolean value).

Upvotes: 1

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