Stumped on C# DateTime ToString() formatting problem

Question

I am getting some junk data returned from a ToString() call on a DateTime object in C# and I'm afraid I'm stumped after poking around with it for a while.

The function is supposed to format dates to be compliant with RFC 822 (as required by the RSS spec) and looks like:

public static string FormatPubDate(DateTime pubDate) 
{
    string _rfc822Format = "ddd, dd MMM yyyy HH:mm:ss";
    string _tmp = pubDate.ToUniversalTime().ToString(_rfc822Format);

    return pubDate.ToString(_tmp + " UT");
}

Which should be what I want, from what I can read of the DateTime ToString() docs.

However, for some dates it's generating junk:

 Console.WriteLine(FormatPubDate(new DateTime(2008, 12, 16, 13, 44, 33)));
 Console.WriteLine(FormatPubDate(new DateTime(2008, 12, 17, 13, 44, 33)));
 Console.WriteLine(FormatPubDate(new DateTime(2009, 3, 18, 4, 17, 20)));
 Console.WriteLine(FormatPubDate(new DateTime(2009, 4, 30, 10, 44, 33)));

Yields:

Tue, 16 Dec 2008 19:44:33 UT
We17, 17 Dec 2008 19:44:33 UT
We18, 18 3ar 2009 09:17:20 UT
T10u, 30 Apr 2009 15:44:33 UT

Any ideas why it's returning We18 instead of Wed and 3ar instead of Mar?

If you take out the ToUniversalTime() call does it work? That could be altering the culture and format strings are culture specific. — John Sheehan, Apr 30 '09 at 16:08
@John -- Nope. I tried that, as well as running my program on a couple of different machines. — Dana, Apr 30 '09 at 16:09

score 12 · Accepted Answer · answered Apr 30 '09 at 16:11

12

You're problem is the last

return pubDate.ToString(_tmp + " UT");

You're doing a second ToString() on the DateTime with the formatted value, as the formatter...

Try changing it to

string _rfc822Format = "ddd, dd MMM yyyy HH:mm:ss";
string _tmp = pubDate.ToUniversalTime().ToString(_rfc822Format);

return _tmp + " UT";

answered Apr 30 '09 at 16:11

Eoin Campbell

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1

Aww, man! I guess this my morning to display my doofusness on the Internet :P – Dana Apr 30 '09 at 16:14
haha... that's pretty much 9am-10am for me... every morning ;) – Eoin Campbell Apr 30 '09 at 16:16
Lol. Why didn't I spot that one? You can add the UT in the format also, so that you don't need the extra concatentation: "ddd, dd MMM yyyy HH:mm:ss' UT'". – Guffa Apr 30 '09 at 16:16

score 3 · Answer 2 · answered Apr 30 '09 at 16:09

3

Can you use this instead?:

String.Format("{0:r}", dt);  // "Sun, 09 Mar 2008 16:05:07 GMT"   RFC1123

answered Apr 30 '09 at 16:09

Mitch Wheat

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Good point. The other posters are correct in identifying the extra ToString() call in your original posted code... – Mitch Wheat Apr 30 '09 at 16:14
Yeah, your formatting is perfect for what I need, and Eoin pointed out my dumb mistake. – Dana Apr 30 '09 at 16:15

score 3 · Answer 3 · answered Apr 30 '09 at 16:11

You are currently calling ToString on the date, passing in your RFC format, then you are calling ToString on the date again, apssing in your already converted date + "UT" as the format, I'm suprised you get anything good coming out!

Try this:

public static string FormatPubDate(DateTime pubDate) 
{
    string _rfc822Format = "ddd, dd MMM yyyy HH:mm:ss";
    return pubDate.ToUniversalTime().ToString(_rfc822Format) + " UT";

}

Stumped on C# DateTime ToString() formatting problem

3 Answers3

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