将字符串转换为货币数字格式，带，不带或不带小数位0

问题描述

我有一个始终会转换为this之类的字符串，在该字符串中，用户输入数字并始终以小数点开头，

所以我有0.01-> 0.10-> 1.00

但是我不想要那样的东西，我只想转换用户输入的内容

这是我现有的将100000转换为1,000.00的代码

func convertme(string: String) -> String{
    var number: NSNumber!
    let formatter = NumberFormatter()
    formatter.numberStyle = .currencyAccounting
    formatter.currencySymbol = ""
    formatter.maximumFractionDigits = 2
    formatter.minimumFractionDigits = 2

    var amountWithPrefix = string

    // remove from String: "$",".",","
    let regex = try! NSRegularExpression(pattern: "[^0-9]",options: .caseInsensitive)
    amountWithPrefix = regex.stringByReplacingMatches(in: amountWithPrefix,options: NSRegularExpression.MatchingOptions(rawValue: 0),range: NSMakeRange(0,string.count),withTemplate: "")
    
    print("amountWithPrefix",amountWithPrefix)

    let double = (amountWithPrefix as Nsstring).doubleValue
    number = NSNumber(value: (double / 100))

    // if first number is 0 or all numbers were deleted
    guard number != 0 as NSNumber else {
        return ""
    }

    return formatter.string(from: number)!
}

预期结果：

我想设置字符串格式的数字而不添加其他数据，我想将（100000.变成100,000。）（100000.0变成100,000.0

我希望将我的100000转换为100,000，并且如果用户也输入了十进制，则只能有一个十进制，因此当用户输入100000.00时，它将转换为100,000.00。

PS。我那里有一个正则表达式，只接受数字但不接受小数，如何使它也接受小数？

解决方法

您可以简单地从原始字符串中过滤非数字或句点，尝试将结果字符串强制为整数。如果成功，则将格式化程序的最大分数位数设置为零，否则将最大分数位数设置为2并将字符串强制为双精度：

extension Formatter {
    static let currency: NumberFormatter = {
        let formatter = NumberFormatter()
        formatter.locale = .init(identifier: "en_US_POSIX")
        formatter.numberStyle = .currencyAccounting
        formatter.currencySymbol = ""
        return formatter
    }()
}

---

extension Numeric {
    var currencyUS: String {
         Formatter.currency.string(for: self) ?? ""
    }
}

---

func convertme(string: String) -> String {
    let string = string.filter("0123456789.".contains)
    if let integer = Int(string)  {
        Formatter.currency.maximumFractionDigits = 0
        return Formatter.currency.string(for: integer) ?? "0"
    }
    Formatter.currency.maximumFractionDigits = 2
    return Double(string)?.currencyUS ?? "0"
}

---

convertme(string: "100000")     // "100,000"
convertme(string: "100000.00")  // "100,000.00"

---

---

编辑/更新： “ 100,000。”这不是有效的数字格式。您需要手动在字符串末尾插入句点。

func convertme(string: String) -> String {
    var string = string.filter("0123456789.".contains)
    // this makes sure there is only one period and keep only the last one in the string
    while let firstIndex = string.firstIndex(of: "."),let _ = string[firstIndex...].dropFirst().firstIndex(of: ".") {
        string.remove(at: firstIndex)
    }
    // get the index of the period in your string
    if let index = string.firstIndex(of: ".") {
        // get the fraction digits count and set the number formatter appropriately
        let fractionDigits = string[index...].dropFirst().count
        Formatter.currency.minimumFractionDigits = fractionDigits
        Formatter.currency.maximumFractionDigits = fractionDigits
        // Number Formatter wont add a period at the end of the string if there is no fractional digits then you need to manually add it yourself
        if fractionDigits == 0 {
            return (Double(string)?.currencyUS ?? "0") + "."
        }
    } else {
        // in case there is no period set the fraction digits to zero
        Formatter.currency.minimumFractionDigits = 0
        Formatter.currency.maximumFractionDigits = 0
    }
    return Double(string)?.currencyUS ?? "0"
}

---

游乐场测试：

convertme(string: "100000")      // "100,000"
convertme(string: "100000.")     // "100,000."
convertme(string: "100000.0")    // "100,000.0"
convertme(string: "100000.00")   // "100,000.00"
convertme(string: "100000.000")  // "100,000.000"