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iOS Swift Basics (retired) Types Printing Results

Posted by Andrew Davis
Andrew Davis
6,367 Points

println challenge question

I’m not sure I’m understanding the question here. It says:

“Given the constant named language, write a println statement which will print the following string: "Learning Swift". (Remember to use the language constant within the string you pass to your println statement).”

I’m given the line:

let language = "Swift"

I added the line:

println("Learning " + language)

My understanding, backed up by replicating the code in an xcode playground, is that this should output the line “Learning Swift” as indicated by the instructions.

I get the feedback that:

“Bummer! You need to interpolate the value of the 'language' constant into the string you pass to ‘println’."

My initial thought from this feedback was that perhaps there was a problem with directly using a constant in the println command, so I then replaced my answer with this code:

var verb = "Learn " var lesson = verb + language println(lesson)

This answer also works in xcode, and also gets the same feedback. I’m afraid I’m at a loss.

println.swift 
let language = "Swift"
var verb = "Learn "
var lesson = verb + language 
println(lesson)

2 Answers

Stone Preston
Stone Preston
42,016 Points
Stone Preston
Stone Preston
42,016 Points

the error states: “Bummer! You need to interpolate the value of the 'language' constant into the string you pass to ‘println’."

you are using string concatenation (joining strings together with the + operator), however you need to use string interpolation:

String interpolation is a way to construct a new String value from a mix of constants, variables, literals, and expressions by including their values inside a string literal. Each item that you insert into the string literal is wrapped in a pair of parentheses, prefixed by a backslash:

the swift eBook provides the following example code:

let multiplier = 3
let message = "\(multiplier) times 2.5 is \(Double(multiplier) * 2.5)"
// message is "3 times 2.5 is 7.5"

so to interpolate the language constant into the string you would use:

let language = "Swift"
println("Learning \(language)")
Andrew Davis
Andrew Davis
6,367 Points
Andrew Davis
Andrew Davis
6,367 Points

Thank you, Stone. I'll give that a try.