DateTime /File question

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csharpula csharp - 24 Mar 2008 13:36 GMT

Hello,
I am trying to add Date and Current time to a name of a log file. I
tried doing this:

string logDateExtention = DateTime.Now.ToShortDateString().ToString() +
DateTime.Now.ToShortTimeString().ToString();

string logName = Data.Name + Data.ProductName + logDateExtention;

And this throws exception during the debug that the name is not legal
probably because of the ":" or "/" . Which format of date will work for
this purpose?

Thanks!

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Jon Skeet [C# MVP] - 24 Mar 2008 13:58 GMT

> I am trying to add Date and Current time to a name of a log file. I
> tried doing this:
>
> string logDateExtention = DateTime.Now.ToShortDateString().ToString() +
> DateTime.Now.ToShortTimeString().ToString();

Are you aware that your extra calls to ToString() are unnecessary
there?

> string logName = Data.Name + Data.ProductName + logDateExtention;
>
> And this throws exception during the debug that the name is not legal
> probably because of the ":" or "/" . Which format of date will work for
> this purpose?

I would go for this:

string logDateExtension = DateTime.Now.ToString("yyyyddMM-HHmmss");

(I'd probably also add ".log" on the end.)

One benefit of that extension is that it sorts nicely - if you sort by
filename, you'll get it sorted by time as well.

You may wish to consider using UtcNow instead of Now, so that things
don't confusing if the timezone is changed, or around daylight savings
time changes.

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Jon Skeet - <skeet@pobox.com>
http://www.pobox.com/~skeet Blog: http://www.msmvps.com/jon.skeet
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Gilles Kohl [MVP] - 24 Mar 2008 14:13 GMT

>Hello,
>I am trying to add Date and Current time to a name of a log file. I
[quoted text clipped - 8 lines]
>probably because of the ":" or "/" . Which format of date will work for
>this purpose?

My suggestion would be someting like YYYYMMDD (maybe separate them using
underlines) because that also sorts well.

Use e.g.

logDateExtension = DateTime.Now.ToString("yyyyMMdd");

or

logDateExtension = DateTime.Now.ToString("yyyy_MM_dd");

Regards,
Gilles.

Reply to this Message

Gilles Kohl [MVP] - 24 Mar 2008 14:22 GMT

>My suggestion would be someting like YYYYMMDD (maybe separate them using
>underlines) because that also sorts well.

[...]

>Use e.g.
>
> logDateExtension = DateTime.Now.ToString("yyyyMMdd");

Oops, didn't see that you also wanted time, but Jon already provided that.

You may want to consider using month-day order for sorting reasons.

Regards,
Gilles.

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BlackWasp - 24 Mar 2008 22:32 GMT

You may want to avoid using yyyymmdd and the like if your application needs
to use the user's preference / locale for formatting. In which case, use
"g" as the format string to combine short date and short time.

Check out my article on DateTime manipulation, which explains the various
formatting options for more info.

http://www.blackwasp.co.uk/CSharpDateManipulation.aspx

Signature

BlackWasp
www.blackwasp.co.uk

> Hello,
> I am trying to add Date and Current time to a name of a log file. I
[quoted text clipped - 12 lines]
>
> *** Sent via Developersdex http://www.developersdex.com ***

Reply to this Message

Jon Skeet [C# MVP] - 24 Mar 2008 22:50 GMT

> You may want to avoid using yyyymmdd and the like if your application needs
> to use the user's preference / locale for formatting. In which case, use
> "g" as the format string to combine short date and short time.

I would say that formatting the *log filename* according to the user's
locale is a recipe for problems. I think this is one case where
localisation shouldn't be applied. In particular, it's very useful for
the support team to be able to know exactly what a filename means when
they get the logs shipped to them.

Signature

Jon Skeet - <skeet@pobox.com>
http://www.pobox.com/~skeet Blog: http://www.msmvps.com/jon.skeet
World class .NET training in the UK: http://iterativetraining.co.uk

Reply to this Message

BlackWasp - 25 Mar 2008 20:44 GMT

Hi Jon,

I agree with you on the concept. Just here the original question included
the use of culture-sensitive information.

I personally would probably use UTC for multi-location systems and have done
with it.

Signature

BlackWasp
www.blackwasp.co.uk

>> You may want to avoid using yyyymmdd and the like if your application
>> needs
[quoted text clipped - 6 lines]
> the support team to be able to know exactly what a filename means when
> they get the logs shipped to them.

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DateTime /File question

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