C# 相当于 imbue 和 numpunct

Question

我正在尝试在 C++ 中找到与以下内容等效的 C#。这纯粹是为了好玩

#include <iomanip>
#include <iostream>
#include <tchar.h>

class CommaSep : public std::numpunct<TCHAR>
{
public:
     CommaSep(TCHAR thousands_sep, const char* grouping)
        :m_thousands_sep(thousands_sep),
         m_grouping(grouping){}
protected:
     TCHAR do_thousands_sep() const{return m_thousands_sep;}
     std::string do_grouping() const {return m_grouping;}
private:
     TCHAR m_thousands_sep;
     std::string m_grouping;
};

int main()
{
    double number = 1234567.1235;
    std::locale comma_locale(std::locale(), new CommaSep(_T(','), "\03"));
    std::locale indian_locale(std::locale(), new CommaSep(_T(','), "\02\02\03"));
    std::locale weird_locale(std::locale(), new CommaSep(_T(','), "\02\01\03"));

    std::wcout.imbue(comma_locale);
    std::wcout << std::setprecision(2) << std::fixed << number << std::endl;
    std::wcout.imbue(indian_locale);
    std::wcout << std::setprecision(2) << std::fixed << number << std::endl;
    std::wcout.imbue(weird_locale);
    std::wcout << std::setprecision(2) << std::fixed << number << std::endl;
}

结果是

1,234,567.12
123,45,67.12
1,234,5,67.12

它完全按照我说的做。我在 C# 中尝试了以下内容。代码要小得多(万岁)，但编译器只是忽略格式并做自己的事情(嘶嘶声)

namespace imbuecs
{
    class Imbue
    {
        static void Main(string[] args)
        {
            int bignum = 123456789;

            System.Console.WriteLine(bignum.ToString("########0"));
            // Indian
            System.Console.WriteLine(bignum.ToString("##,###,##,#0"));
            System.Console.WriteLine(bignum.ToString("###,###,##0"));
            // Chinese
            System.Console.WriteLine(bignum.ToString("#,####,###0"));
        }
    }
}

我得到的是

123456789
123,456,789  expected 12,345,67,89
123,456,789
123,456,789  expected 1,2345,6789

我可以为此编写大量代码，但我想知道是否有一种简单的方法可以做到这一点。

Answer 1

来自 the documentation ，在指定自定义格式时，逗号(强调我的):

Serves as both a group separator and a number scaling specifier. As a group separator, it inserts a localized group separator character between each group. As a number scaling specifier, it divides a number by 1000 for each comma specified.

所以它导致数字被分组为 3 位数字。如果您想制作自己的格式，则需要将逗号括在单引号中以将其呈现为文字字符串。例如:

Console.WriteLine(bignum.ToString("##','###','##','#0"));
Console.WriteLine(bignum.ToString("#','####','###0"));

将输出:

12,345,67,89
1,2345,6789

另一种选择是将 NumberFormatInfo 对象与 NumberGroupSizes 一起使用属性(property)。例如:

var nfi = new System.Globalization.NumberFormatInfo();
//First group is 2 digits, the rest are 3 digits
nfi.NumberGroupSizes = new int[] { 2, 3 }; 

Console.WriteLine(bignum.ToString("#,#0", nfi));