Quirk in the DateTime class

Jakob Andersen

1/5/2008 8:49:20 PM #

The escaping isn't so strange the first slash is to escape the second \ from the C# compilers string handling so this would also work:

string date = DateTime.Now.ToString(@"yyyy-MM-dd HH\:mm")

The reason for ":" needed to be escaped is that it is the way you specify a timeseparator in a DateTime format string, the same goes for "/" which is the date seperator in a formatstring. The time and dateseparators can be found on CultureInfo.DateTimeFormat.TimeSeperator and CultureInfo.DateTimeFormat.DateSeperator and they are different that ":" and "/" for many cultures which easily can be determined by looping over the specific cultures using the following code:

foreach(CultureInfo ci in CultureInfo.GetCultures(CultureTypes.SpecificCultures)){
        if(ci.DateTimeFormat.TimeSeparator != ":"){
          Console.WriteLine("Time: " + ci.Name + " " + ci.DateTimeFormat.TimeSeparator);
        }
        if(ci.DateTimeFormat.DateSeparator != ":"){
          Console.WriteLine("Date: " + ci.Name + " " + ci.DateTimeFormat.DateSeparator);
        }
      }

ck

1/5/2008 11:24:27 PM #

If you read the documentation:
msdn2.microsoft.com/en-us/library/w2sa9yss.aspx

You see that the culture's settings are taken into account, which is why it removed the : for you.  Where as the strait tostring does not.

So it was doing what it was supposed to do.

The other issue (the need for a double escape) is just poor programming on somebody's part at Redmond.

Tommy Carlier

1/6/2008 6:32:37 AM #

If you want culture-independent formatting, you could use the invariant culture, like this:
string date = DateTime.Now.ToString("yyyy-MM-dd HH:mm", CultureInfo.InvariantCulture);

Jakob Andersen

1/6/2008 10:48:12 AM #

Escaping with the single slash would work if you Add @ before the string as i wrote, the first escaping is for C# to understand that you have a backslash in you string.

Jakob Andersen

1/6/2008 10:56:27 AM #

The problem is you used ":" which is special in datatime format string, the same is "/" so i would argue it returned correctly. What you want is to format it using no culture specific settings and that is done using Tommy's suggestion.

Cristiano

1/6/2008 12:08:08 PM #

I have linked the post near the Italian forum of BlogEngine.Net:
www.italianbloggers.it/forum/viewforum.php?f=19

Thanks a lot to all

Nicolas Cadilhac

1/8/2008 1:47:27 PM #

as other specified, this is not an error at all that your ':' character has been replaced. This is the way it is supposed to work. The ':' character is parsed and understood as "the time separator for the current culture" the same way as 'd' is understood as the day of the month. If you want explicitely a particular character you can put it inside single quotes, so your format string would be yyyy-MM-dd HH':'mm.

Krzysztof Koźmic

1/18/2008 6:26:59 AM #

If you don't specify which culture should be used, the CultureInfo.CurrentCulture will be used to display the string, and basically, what Nicolas said happends. If you want to make sure that ALWAYS string will look the same you should use Tommy Carlier's solution: it's the most right and the most elegant. Your character escaping is more of a hack ;)

Krzysztof Koźmic

1/18/2008 9:11:50 AM #

You may be interested in blog post I wrote regarding this issue: kozmic.pl/.../...-datetime.tostring-explained.aspx

Lucas

1/19/2008 12:58:35 AM #

the colon is considered a special code, same with "d", "m", etc. for example, if you wanted an actual "d" in the string output, you would have to escape them as "\d" (plus any escaping needed for the backslashes)

"yyyy-M-d" => "2008-1-18"
"yyyy-\M-\d" => "2008-M-d"

the colon is replaced with the culture's time separator the same way 'M' and 'd' are replaced.