Swift specify double without converting to string

Question

I want to specify my (slider) double to 2 decimals but xcode won't let me do that:

return (Double(pris, specifier: "%.2f"))

And i don't want to convert it into a string and then format it because numbers like 600000000 are then unreadable.

I have tried solutions like :

extension Double {
// Rounds the double to 'places' significant digits
  func roundTo(places:Int) -> Double {
    guard self != 0.0 else {
        return 0
    }
    let divisor = pow(10.0, Double(places) - ceil(log10(fabs(self))))
    return (self * divisor).rounded() / divisor
  }
}

Does this answer your question? [Rounding a double value to x number of decimal places in swift](https://stackoverflow.com/questions/27338573/rounding-a-double-value-to-x-number-of-decimal-places-in-swift) — Joakim Danielson, Jan 24 '20 at 11:52
**And i don't want to convert it into a string and then format it because numbers like 600000000 are then unreadable.** 600000000 is an Integer. If you give 600000000.00 then it will work for sure. — Keshu R., Jan 24 '20 at 12:15
`but xcode won't let me do that` - what do you mean by that? — Cristik, Jan 24 '20 at 12:19
sorry if i was unclear, it gives 600000000.0000000 right now — oscar, Jan 24 '20 at 12:34
If that link doesn't help then you need to clarify what you are asking — Joakim Danielson, Jan 24 '20 at 12:34
I have around 5 sliders (doubles) which then are calculated together for an output. This output gives a lot of decimals. — oscar, Jan 24 '20 at 16:00
As mentioned in Joakim's link/comment, always round first then format & recast to string. — P2000, Jan 24 '20 at 20:15

Rob C · Answer 1 · 2020-01-24T12:50:21.797

1

This should do what you need:

extension Double {
    func roundedTo(places: Int) -> Double {
        let conversion = pow(10.0, Double(places))
        return (self * conversion).rounded() / conversion
    }
}

print(10.125.roundedTo(places: 2)) // prints 10.13
print(10.124.roundedTo(places: 2)) // prints 10.12

edited Jan 24 '20 at 12:50

answered Jan 24 '20 at 12:34

Rob C

4,877
1
11
24

Fatal error: Double value cannot be converted to Int because it is either infinite or NaN – oscar Jan 24 '20 at 12:38
sorry no, still 6 decimals – oscar Jan 24 '20 at 15:52
Correct: `print(1.999.roundedTo(places: 2))` gives 2.0 – P2000 Jan 24 '20 at 20:12

score 1 · Answer 2 · answered Jan 24 '20 at 12:49

1

let b: Double = Double(600000000.376)
let result = Double(round(100*b)/100)
print(result) // prints 600000000.38

answered Jan 24 '20 at 12:49

Suresh Vutukuru

211
2
8

Correct: `> let result = Double(round(100*b)/100)` result: Double = 600000000.38 – P2000 Jan 24 '20 at 20:13

score 0 · Answer 3 · answered Jan 25 '20 at 12:19

0

The simple solution was to remove the (Double) before the calculation.

return (Double(pris, specifier: "%.2f"))

should be only

pris, specifier: "%.2f")

answered Jan 25 '20 at 12:19

oscar

101
1
1
7

Swift specify double without converting to string

3 Answers3