CODEWITHSUNDEEP
swift3chaining
duffer01
duffer01

Reputation: 1

How to minimize optionals

I want to input a number as a string and am using readLine which returns a String?. Then I want to convert that inputed String to an Int which also returns an Int?. If either optional returns a nil, then print an error; otherwise, use the Int. The following code works but there has to be a better way. Any ideas?

print ("Enter number: ", terminator:"")
let number = readLine ()

if number != nil && Int (number!) != nil
{
    let anInt = Int (number!)!
}
else
{
    print ("Input Error")
}

Upvotes: 0

Views: 48

Answers (1)

Rob
Rob

Reputation: 437381

You can combine the unwrapping of readLine response and the conversion to Int and making sure the numeric conversion succeeded into a single guard statement, e.g., 

guard let string = readLine(), let number = Int(string) else {
    print("input error")
    return
}

// use `number`, which is an `Int`, here

You can obviously spin that around if you want:

if let string = readLine(), let number = Int(string) {
    // use `number`, which is an `Int`, here
} else {
    print("input error")
}

Upvotes: 3

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