Convert String Values From Server Formatted as Double To Int

Question

Im working with a service that send back values of type String which contains floating point like Double as so for example "1240.86". I want to cast it to Int and when i try to convert like so Int(stringObject) the cast fails when the values have floating points. How can i cast it? Thanks!

just a note, that is not casting but converting. Have you tried *converting* the string to a double and go from there? — luk2302, Jul 17 '17 at 15:25
Thats my solution now but i was looking for more elegant way — orthehelper, Jul 17 '17 at 15:28

score 3 · Accepted Answer · answered Jul 17 '17 at 15:30

3

Try it in two steps:

if let aDouble = Double(someString) {
    let someInt = Int(aDouble)
}

or possibly:

let someInt = Int(Double(someString) ?? 0)

though the latter is a bit of a kludge since you probably don't want to force a value of 0 if the string isn't a valid number.

answered Jul 17 '17 at 15:30

rmaddy

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Yeah, I wouldn't go with the latter because it is impossible to distinguish a string `"0"` from an invalid number. – JeremyP Jul 17 '17 at 15:56
I would also add `let someInt = Int(round(aDouble))` as option – Vasilii Muravev Jul 17 '17 at 16:48
@VasiliiMuravev Whether the `Double` should be rounded or not is a separate decision and not really important to the question. – rmaddy Jul 17 '17 at 16:49

dfrib · Answer 2 · 2017-07-17T16:04:22.330

2

You could use the map(_:) method of Optional to optionally chain a conversion (initialization by, specifically) from String to Double followed by one from Double to Int and conditionally bind the resulting integer in case it is not nil (i.e. successfully converted):

let str = "1240.86"
if let number = Double(str).map(Int.init) {
    // number is of type Int and, in this example, of value 1240
}

edited Jul 17 '17 at 16:04

answered Jul 17 '17 at 15:59

dfrib

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@down voter: consider giving feedback rather than a drive-by down vote. Or is this just an anger down vote ...? – dfrib Jul 17 '17 at 16:46
I didn't know about the `Optional map` function. I like this. – rmaddy Jul 17 '17 at 16:53
@rmaddy most of the time its use cases can be replaced simply by optional chaining, but for cases such as this one it can be a good approach. Also note that there's a `flatMap(_:)` method of `Optional` which can also sometimes be of use (passes the single argument as an optional without unwrapping it). – dfrib Jul 17 '17 at 17:00

Vasilii Muravev · Answer 3 · 2017-07-17T16:27:20.203

0

You can separate string by dot .:

func printInt(from str: String) {
    let intValue = Int(str.components(separatedBy: ".")[0]) ?? 0
    print(intValue)
}

printInt(from: "1234.56")   // 1234
printInt(from: "1234")      // 1234
printInt(from: "0.54")      // 0
printInt(from: ".54")       // 0
printInt(from: "abc")       // 0

edited Jul 17 '17 at 16:27

answered Jul 17 '17 at 16:18

Vasilii Muravev

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Convert String Values From Server Formatted as Double To Int

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