I need to separate Int values with commas every 3 digits in Swift.
I have tried to do this with NumberFormatter, but it sometimes returns unexpected results with large digits.
Why is this?
import Foundation
func format(_ num: Int) -> String {
let formatter = NumberFormatter()
formatter.numberStyle = .decimal
formatter.groupingSeparator = ","
formatter.groupingSize = 3
return formatter.string(from: NSNumber(value: num)) ?? String(num)
}
let num1 = 199_999_999_999_999
let num2 = 1_999_999_999_999_999
let num3 = 19_999_999_999_999_999
let num4 = 199_999_999_999_999_999
let num5 = 1_999_999_999_999_999_999
print(format(num1))
print(format(num2))
print(format(num3))
print(format(num4))
print(format(num5))
// 199,999,999,999,999
// 1,999,999,999,999,999
// 20,000,000,000,000,000 <- unexpected results
// 199,999,999,999,999,999
// 1,999,999,999,999,999,999