英文:
Convert string to number using NumberFormatter not returning expected number
问题
let formatter = NumberFormatter()
let sample1 = formatter.number(from: "29.99") ---> 29.99
let sample2 = formatter.number(from: "79.99") ---> 79.98999999999999
But I expect to get 79.99 as the result of sample2
Tried using different rounding modes with no help
英文:
let formatter = NumberFormatter()
let sample1 = formatter.number(from: "29.99") ---> 29.99
let sample2 = formatter.number(from: "79.99") ---> 79.98999999999999
But I expect to get 79.99 as the result of sample2
Tried using different rounding modes with no help
答案1
得分: 0
这是因为一个浮点数。您可以在这里查看什么是FPN。
如果您需要四舍五入到2位小数，您可以使用此扩展链接：
extension NSNumber {
func rounded(to decimalPlaces: Int) -> Double {
let multiplier = pow(10, Double(decimalPlaces))
return (Double(truncating: self) * multiplier).rounded(.toNearestOrEven) / multiplier
}
}
let sample1 = formatter.number(from: "29.99")?.rounded(to: 2) --> 将是 Optional(29.99)
let sample2 = formatter.number(from: "79.99")?.rounded(to: 2) --> 将是 Optional(79.99)
英文:
This happens because a Floating Point Number. You can see what is FPN in here
If you need 2 decimal value with round , you can use this extension link
extension NSNumber {
func rounded(to decimalPlaces: Int) -> Double {
let multiplier = pow(10, Double(decimalPlaces))
return (Double(truncating: self) * multiplier).rounded(.toNearestOrEven) / multiplier
}
}
let sample1 = formatter.number(from: "29.99")?.rounded(to: 2) --> will be Optional(29.99)
let sample2 = formatter.number(from: "79.99")?.rounded(to: 2) --> will be Optional(79.99)
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