DateTime很奇怪

Question

How come

w.WriteLine(Program.RegisterList[i].DateTime);

Writes : 11/20/2013 01:46:31 PM

But

w.WriteLine(Convert.ToDateTime(Program.RegisterList[i].DateTime, CultureInfo.InvariantCulture).ToString());

Writes 20/11/2013 1:46:31 PM

? Isn't invariant culture supposed to make it MM/DD/YY? I would like to use the invariant culture method incase a date slips by in DD/MM/YY format.

Thanks!

Edit: I should mention Program.RegisterList[i].DateTime is a string.

Edit2:

MessageBox.Show("11/20/2013 01:46:31 PM");
MessageBox.Show(Convert.ToDateTime("11/20/2013 01:46:31 PM", CultureInfo.InvariantCulture).ToString());

Answer 1

 w.WriteLine(Convert.ToDateTime(Program.RegisterList[i].DateTime, CultureInfo.InvariantCulture).ToString());

You confused yourself by writing code you can't understand anymore. A simple rewrite of that one honking statement:

string s = Program.RegisterList[i].DateTime;
DateTime dt = Convert.ToDateTime(s, CultureInfo.InvariantCulture);
w.WriteLine(dt);

Which should now make it obvious that you are not using InvariantCulture to display the date, it uses the default culture. Which on your machine puts the day first.

Always write readable code, it is not slower.

Answer 2

CultureInvariant only guarantees that the format won't change across cultures - it should not be used to display data, only to persist data. If you're concerned about how a string is displayed, you should use a specific culture that displays how you want. More from MSDN

Having said that, I'm not sure what you mean by a "date slipping by" in a different format. Are you reading a list of dates, and some are in different format? If so, I'm afraid CultureInvariant is not the answer.