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Parsing floating point strings with specified decimal separator

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4.53 (21 votes)
9 Apr 2003
Parsing strings in .NET is very easy, but if you want to specify different decimal separators, there might be some confusion.


Everyone knows that "everything is easy in .NET" and in most cases it really is. This also applies to string parsing issues. When you want to convert string "123.4" into value 123.4, you usually write code looking like:

double someNumber;
string myNumber = "123.4";

    someNumber = double.Parse(myNumber);
    //something's wrong
    //that is not a number

In most cases it works with no trouble. Until your string is not a number or... decimal separator is different than one defined in your system.

Let's assume that your system decimal separator is a comma (",") and you want to parse string with dot (".") separator - there's no way. An exception is thrown (and you are happy that try-catch works :) ).

There is of course an easy way to parse strings with decimal separator you want to use. The Parse method allows to define additional parameter - IFormatProvider. If you put NumberFormatInfo object as a second parameter of Parse method, you can specify what decimal separator should be used.

According to MSDN you can obtain current thread NumberFormatInfo by CurrentInfo static property. There is some confusion because CurrentInfo is a read-only property and you would like to modify the decimal separator.

There's a little "walk around" - use current CultureInfo, "clone" its NumberFormatInfo and modify the decimal separator:

class ParserClass
    static System.Globalization.NumberFormatInfo ni = null;
    public ParserClass()
       System.Globalization.CultureInfo ci = 
       ni = (System.Globalization.NumberFormatInfo)
       ni.NumberDecimalSeparator = ".";
    public someMethod()
        double someNumber;
        string myNumber = "123.4";
            someNumber = double.Parse(myNumber,ni);

Using static variable ni allows you to use it whenever you parse string with "." decimal separator (assuming that instance of ParserClass is created).


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About the Author

Marcin Cuprjak
Poland Poland
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Comments and Discussions

GeneralMy vote of 5 Pin
JElnur3-Nov-11 20:00
memberJElnur3-Nov-11 20:00 
GeneralMy vote of 5 Pin
minhtruc20-Jun-11 17:36
memberminhtruc20-Jun-11 17:36 
GeneralOr you do not care... Pin
rroestenburg5-Oct-07 2:00
memberrroestenburg5-Oct-07 2:00 
GeneralRe: Or you do not care... Pin
Toumar5-Aug-09 11:28
memberToumar5-Aug-09 11:28 
Generalchange regional (language) Pin
hamid_m17-Feb-07 9:55
memberhamid_m17-Feb-07 9:55 
QuestionChanging the locale? Pin
QmQ28-May-06 12:34
memberQmQ28-May-06 12:34 
AnswerRe: Changing the locale? Pin
Marcin Cuprjak29-May-06 10:51
memberMarcin Cuprjak29-May-06 10:51 
GeneralRe: Changing the locale? Pin
QmQ29-May-06 11:04
memberQmQ29-May-06 11:04 
GeneralStatic constructor Pin
Steve Hansen10-May-06 2:49
memberSteve Hansen10-May-06 2:49 
GeneralERROR Pin
sgomcres9-Feb-06 5:26
membersgomcres9-Feb-06 5:26 
GeneralSupporting both . and , Pin
Mattias Olgerfelt1-Sep-04 2:05
memberMattias Olgerfelt1-Sep-04 2:05 
GeneralRe: Supporting both . and , Pin
17-Jun-05 0:38
suss17-Jun-05 0:38 
GeneralRe: Supporting both . and , Pin
Michal Rorat17-Jun-05 1:19
memberMichal Rorat17-Jun-05 1:19 
GeneralRe: Supporting both . and , Pin
Mattias Olgerfelt17-Jun-05 1:45
memberMattias Olgerfelt17-Jun-05 1:45 
GeneralHint Pin
Grommel21-Apr-04 2:19
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GeneralDracula Pin
LeonJ16-Apr-03 0:29
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GeneralComment Pin
John O'Byrne11-Apr-03 1:35
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GeneralRe: Comment Pin
Tim Smith11-Apr-03 2:19
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GeneralRe: Comment Pin
John O'Byrne11-Apr-03 4:16
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Posted 9 Apr 2003


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