c# - string.Format(..., double) 后跟 double.Parse 使用相同的 NumberFormatInfo 会导致 FormatException。为什么？

Question

NumberFormatInfo nfi = new NumberFormatInfo()
{
    CurrencySymbol = "$$s. ",
    CurrencyGroupSeparator = ".",
    CurrencyDecimalSeparator = ",",
    NegativeSign = "-",
    CurrencyNegativePattern = 2
};

double amount = double.Parse("$$s. 1.123,00", nfi);

最后一行抛出FormatException，我不知道为什么。我试图解析的字符串实际上来自于:

String.Format(nfi, "{0:C}", 1123.00)

Answer 1

您并没有告诉它应该接受货币值。为此，您需要调用接受 NumberStyles 值的重载，并包含 NumberStyles.AllowCurrencySymbol。例如:

using System;
using System.Globalization;

class Test
{
    static void Main()
    {
        NumberFormatInfo nfi = new NumberFormatInfo()
        {
            CurrencySymbol = "$$s. ",
            CurrencyGroupSeparator = ".",
            CurrencyDecimalSeparator = ",",
            NegativeSign = "-",
            CurrencyNegativePattern = 2
        };

        double d = double.Parse("$$s. 1.123,00",
            NumberStyles.Number | NumberStyles.AllowCurrencySymbol,
            nfi);
        Console.WriteLine(d);
    }
}

请注意，货币值通常用十进制表示比用 double 表示更好。