Reading a date from xlsx using open xml sdk

Question

I have a date in format \"4/5/2011\" (month/day/year) in a xlsx file in one of the cells. Im trying to parse the file and load those data in some classes.

So far the

Answer 1

Adding my 2 pence worth. I am processing a template, so I know a given cell is meant to be a DateTime. So I end up in this method with a string parameter excelDateTime containing the cell value, which typically will be a OADate number like "42540.041666666664".

public static bool TryParseExcelDateTime(string excelDateTimeAsString, out DateTime dateTime)
{
    double oaDateAsDouble;
    if (!double.TryParse(excelDateTimeAsString, out oaDateAsDouble)) //this line is Culture dependent!
        return false;
    //[...]
    dateTime = DateTime.FromOADate(oaDateAsDouble);

My problem is that the end user is in Germany, and because this is a website, we've set the Thread.CurrentThread.CurrentCulture and Thread.CurrentThread.CurrentUICulture to "DE-de". And when you call double.TryParse, it uses the culture to parse the number. So this line: double.TryParse("42540.041666666664", out oaDate) does indeed work, but it returns 42540041666666664 as in Germany the dot is a group separator. DateTime.FromOADate then fails because the number is out of range (minOaDate = -657435.0, maxOaDate = +2958465.99999999).

This make me think that:

1. regardless of the locale on a user's machine, the OpenXML document contains numbers formatted in a default locale (US? invariant? in any case, with the dot as a decimal separator). I've searched, but not found the spec for this.
2. when doing double.TryParse on a potential OADate string, we should do it with double.TryParse(excelDateTimeAsString, NumberStyles.Any, CultureInfo.InvariantCulture, out oaDateAsDouble)). I'm using CultureInfo.InvariantCulture, but it should be whatever point 1 is, which I don't know for sure.