c# - 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?

Answer 1

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).