如何在C＃中重新格式化表示小数的字符串，以便有空格组分隔符？

How in C# to reformat string, representing a decimal, to have space group separator?

我在一些文章中发现，在将小数(或其他数字数据类型)转换为字符串的过程中，关于格式化字符串、表示数字、使用数字组分隔符的文章：

如何在C中格式化1700到1700和1000000到1000'000？

C：格式化价格值字符串

如果这些数字已经是字符串格式(通过streamreader从.txt文件中读取)，但仍然希望使用组分隔符(和字符串格式)，该怎么办？

在这种情况下，将它解析为十进制然后返回到具有所需格式的字符串是最合理的方法吗？

我想其他的。我有另一种格式化字符串值的方法。
您可以检查它：

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''' <summary>
''' Parses and formats a string value
''' </summary>
''' <param name="value">The value to check and format</param>
''' <param name="f_bAddGroupSep">Specifies the formater whether adds more group separator to formatted value string</param>
''' <returns></returns>
''' <remarks></remarks>
Private Function ParseValue(ByVal value As String, _
Optional ByVal f_bAddGroupSep As Boolean = True) As String
'If invalid number
Dim f_decValue As Decimal = 0
If (String.IsNullOrEmpty(value, StringAction.Trim) _
OrElse (Not (Decimal.TryParse(Trim(value), NumberStyles.Number, Me.Culture, f_decValue)))) Then Return"0"
'Trims value
value = Trim(value)
'If not negative, remove the negative signal
If (Not (Me.IsNegative)) Then value = Replace(value, Me.NumberFormat.NegativeSign, vbNullString)
'Starts formating value
Dim f_iDecNum As Int32 = 0
Dim f_decRndValue As Decimal = 0
Dim f_sNumPat As String = vbNullString
If (Me.IsDecimal) Then
'Parses the decimal digits number
f_iDecNum = Me.NumberFormat.NumberDecimalDigits
If (Me.DecimalDigits >= 0) Then f_iDecNum = Me.DecimalDigits
'If the formatted value had the decimal separator signal
If (IndexOf(value, Me.NumberFormat.NumberDecimalSeparator) >= 0) Then
value &= New String("0"c, f_iDecNum)

'Else (If the formatted value did not have the decimal separator signal)
Else
value &= String.Concat(Me.NumberFormat.NumberDecimalSeparator, New String("0"c, f_iDecNum))
End If
'Prepares the number format pattern
f_sNumPat = String.Concat("N", Convert.ToString(f_iDecNum))

'Else
Else
'Prepares the number format pattern
f_sNumPat ="N"
End If
Try
'Casts the string value to decimal
f_decValue = Convert.ToDecimal(value, Me.Culture)
'Prepares the rounded decimal value
f_decRndValue = f_decValue
Select Case Me.Round
'Rounds down
Case Util.NumberFormat.RoundDown
f_decRndValue = Decimal.Round(f_decValue, f_iDecNum)
If (f_decRndValue <> f_decValue) Then f_decRndValue = Decimal.Round((f_decValue - Convert.ToDecimal(String.Concat("0", Me.NumberFormat.NumberDecimalSeparator, New String("0"c, f_iDecNum),"5"), Me.NumberFormat)), f_iDecNum)
'Rounds up
Case Util.NumberFormat.RoundUp
f_decRndValue = Decimal.Round(f_decValue, f_iDecNum)
If (f_decRndValue <> f_decValue) Then f_decRndValue = Decimal.Round((f_decValue + Convert.ToDecimal(String.Concat("0", Me.NumberFormat.NumberDecimalSeparator, New String("0"c, f_iDecNum),"5"), Me.NumberFormat)), f_iDecNum)
'Rounds by the decimal digits number
Case Util.NumberFormat.HalfAdjust
f_decRndValue = Decimal.Round(f_decValue, f_iDecNum)
'Rounds up
If (f_decRndValue > f_decValue) Then
f_decRndValue = Decimal.Round((f_decValue + Convert.ToDecimal(String.Concat("0", Me.NumberFormat.NumberDecimalSeparator, New String("0"c, f_iDecNum),"5"), Me.NumberFormat)), f_iDecNum)

'Else (Rounds down)
ElseIf (f_decRndValue < f_decValue) Then
f_decRndValue = Decimal.Round((f_decValue - Convert.ToDecimal(String.Concat("0", Me.NumberFormat.NumberDecimalSeparator, New String("0"c, f_iDecNum),"5"), Me.NumberFormat)), f_iDecNum)
End If
End Select
'Returns the formatted decimal value
value = f_decRndValue.ToString(f_sNumPat, Me.Culture)
Catch ex As Exception
f_decValue = 0
f_decRndValue = 0
value ="0"
End Try
Return value
End Function

使用属性：
----------------
me.isdecimal：指定是否将字符串值格式化为十进制数
me.isnegative：指定是否接受负十进制值
me.culture:您的文化信息
me.numberFormat：数字格式信息。它来自Me.Culture(=Me.Culture.NumberFormat)
Me.Round：舍入小数的方法(向上舍入、向下舍入或半调整(按十进制数字舍入))
me.decimal digits：小数位数

出于好奇，我把这个方法放在一起，看看在不解析和格式化的情况下向字符串添加分隔符需要什么：

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public static string AddGroupSeparators(string number) {
int[] sizes = CultureInfo.CurrentCulture.NumberFormat.NumberGroupSizes;
int pos = number.LastIndexOf(CultureInfo.CurrentCulture.NumberFormat.NumberDecimalSeparator);
if (pos == -1) pos = number.Length;
int sizeIndex = 0;
while (sizes[sizeIndex] > 0 && pos > sizes[sizeIndex]) {
pos -= sizes[sizeIndex];
number = number.Insert(pos, CultureInfo.CurrentCulture.NumberFormat.NumberGroupSeparator);
if (sizeIndex < sizes.Length - 1) sizeIndex++;
}
return number;
}