How to convert string to double with proper cultureinfo

Question

I have two nvarchar fields in a database to store the DataType and DefaultValue  and I have a DataType Double and value as 65 89875 in English format   Now I want the user to see the value as per the selected browser language format  65 89875 in English should be displayed as 65 89875 in German   Now if the user edits from German format to 65 89875 which is 65 89875 equivalent in English  and the other user views from an English browser it comes as 6589875   This happens because in the database it was stored as 65 89875 in the nvarchar column and when converted using English culture it becomes 6589875 since it considers   as a separator which is a decimal operator for German   How do I get this working for all the browsers

User · Answer

I have this function in my toolbelt since years ago (all the function and variable names are messy and mixing Spanish and English, sorry for that).

It lets the user use , and . to separate the decimals and will try to do the best if both symbols are used.

    Public Shared Function TryCDec(ByVal texto As String, Optional ByVal DefaultValue As Decimal = 0) As Decimal

        If String.IsNullOrEmpty(texto) Then
            Return DefaultValue
        End If

        Dim CurAsTexto As String = texto.Trim.Replace("$", "").Replace(" ", "")

        ''// You can probably use a more modern way to find out the
        ''// System current locale, this function was done long time ago
        Dim SepDecimal As String, SepMiles As String
        If CDbl("3,24") = 324 Then
            SepDecimal = "."
            SepMiles = ","
        Else
            SepDecimal = ","
            SepMiles = "."
        End If

        If InStr(CurAsTexto, SepDecimal) > 0 Then
            If InStr(CurAsTexto, SepMiles) > 0 Then
                ''//both symbols was used find out what was correct
                If InStr(CurAsTexto, SepDecimal) > InStr(CurAsTexto, SepMiles) Then
                    ''// The usage was correct, but get rid of thousand separator
                    CurAsTexto = Replace(CurAsTexto, SepMiles, "")
                Else
                    ''// The usage was incorrect, but get rid of decimal separator and then replace it
                    CurAsTexto = Replace(CurAsTexto, SepDecimal, "")
                    CurAsTexto = Replace(CurAsTexto, SepMiles, SepDecimal)
                End If
            End If
        Else
            CurAsTexto = Replace(CurAsTexto, SepMiles, SepDecimal)
        End If
        ''// At last we try to tryParse, just in case
        Dim retval As Decimal = DefaultValue
        Decimal.TryParse(CurAsTexto, retval)
        Return retval
    End Function

User · Answer

You can change your UI culture to anything you want  but you should change the number separator like this   CultureInfo info   new CultureInfo  fa-IR    info NumberFormat NumberDecimalSeparator        Thread CurrentThread CurrentCulture   info  Thread CurrentThread CurrentUICulture   Thread CurrentThread CurrentCulture    With this  your strings converts like this   12 49  instead of  12 49  or  12 49

User · Answer

I took some help from MSDN  but this is my answer   double number  string localStringNumber  string doubleNumericValueasString    65 89875   System Globalization NumberStyles style   System Globalization NumberStyles AllowDecimalPoint   if  double TryParse doubleNumericValueasString  style  System Globalization CultureInfo InvariantCulture  out number       Console WriteLine  Converted   0   to  1     doubleNumericValueasString  number   else     Console WriteLine  Unable to convert   0      doubleNumericValueasString   localStringNumber  number ToString System Globalization CultureInfo CreateSpecificCulture  de-DE

User · Answer

Convert ToDouble x  can also have a second parameter that indicates the CultureInfo and when you set it to System Globalization CultureInfo InvariantCulture the result will allways be the same

User · Answer

Use InvariantCulture  The decimal separator is always  quot   quot  eventually you can replace  quot   quot  by  quot   quot  When you display the result   use your local culture  But internally use always invariant culture TryParse does not allway work as we would expect There are change request in  net in this area  https   github com dotnet runtime issues 25868

User · Answer

You can convert the value user provides to a double and store it again as nvarchar  with the aid of FormatProviders  CultureInfo is a typical FormatProvider  Assuming you know the culture you are operating   System Globalization CultureInfo EnglishCulture   new System Globalization CultureInfo  en-EN    System Globalization CultureInfo GermanCulture   new System Globalization CultureInfo  de-de      will suffice to do the neccesary transformation  like   double val  if double TryParse  65 89875   System Globalization NumberStyles Float  GermanCulture   out val         string valInGermanFormat   val ToString GermanCulture       string valInEnglishFormat   val ToString EnglishCulture      if double TryParse  65 89875   System Globalization NumberStyles Float  EnglishCulture   out val         string valInGermanFormat   val ToString GermanCulture       string valInEnglishFormat   val ToString EnglishCulture

User · Answer

You need to define a single locale that you will use for the data stored in the database  the invariant culture is there for exactly this purpose   When you display convert to the native type and then format for the user s culture   E g  to display   string fromDb    123 56   string display   double Parse fromDb  CultureInfo InvariantCulture  ToString userCulture     to store   string fromUser    132 56   double value     Probably want to use a more specific NumberStyles selection here  if   double TryParse fromUser  NumberStyles Any  userCulture  out value          Error      string forDB   value ToString CultureInfo InvariantCulture     PS  It  almost  goes without saying that using a column with a datatype that matches the data would be even better  but sometimes legacy applies

[c#] How to convert string to double with proper cultureinfo

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