CODEWITHSUNDEEP
iosswift
REALFREE
REALFREE

Reputation: 4396

arithmetic within string literal in Swift

Playing with Swift, I found something awkward error.

let cost = 82.5
let tip = 18.0
let str = "Your total cost will be \(cost + tip)"

This works fine as I expect, but

let cost = 82.5
let tip:Float = 18
let str = "Your total cost will be \(cost + tip)"

would not work with error 

could not find member 'convertFromStringInterpolationSegment' 
let str = "Your total cost will be \(cost + tip)"

The difference between two example is declaring tip constant to explicitly float or not. Would this be reasonable result?

Upvotes: 1

Views: 1562

Answers (3)

Priyanka
Priyanka

Reputation: 543

Values are never implicitly converted to another type.

let cost = 82.5
let tip:Float = 18
let str = "Your total cost will be \(cost + tip)"

In the above example it is considering cost as double & you have defined tip as float, so it is giving error.

Rather specify the type of cost as float as shown below 

let cost:Float = 82.5

Hope it will solve your problem.

Upvotes: 1

Analog File
Analog File

Reputation: 5316

In your code cost in inferred to be of type Double.

In your first (working) example tip is also inferred to be Double and the expressions cost + tip is an addition of two Double values, resulting in a Double value.

In your second (not working) example tip is declared to be Float therefore the expressions cost + tip is an error. The error message is not very informative. But the problem is that you are adding a Double to a Float and in a strongly statically typed language you will not have automatic type conversions like you had in C or Objective C.

You have to do either Float(cost) + tip or cost + Double(tip)

Upvotes: 0

mythz
mythz

Reputation: 143319

You still need to cast the numbers into the same type so they can be added together, e.g:

let cost = 82.5
let tip:Float = 18
let str = "Your total cost will be \(Float(cost) + tip)"

By default real number literals are inferred as Double, i.e:

let cost:Double = 82.5

So they need to be either explicitly cast to a Double or a Float to be added together.

Upvotes: 4

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