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Generate Unique ID following a specific pattern like "digitStringDigit" in C#

Answer 1

+2 A:

If I wanted a purely unique ID I would use:

 TimeSpan uniqueID = DateTime.Now.ticks;

Which guarnatees you get a unique ID regardless of when you call it.

Michael Eakins 2010-10-02 12:39:22

what if someone turn back the clock?

kofucii 2010-10-02 13:05:59

datetime.now.ticks utilizes the CMOS clock internal to the PC. Unless your users are going to make major physical changes to the PC's this should be a very safe method of generating a Unique ID

Michael Eakins 2010-10-02 13:19:39

That clock is still the same one that is set by the user.

Tergiver 2010-10-02 15:31:02

You don't understand. The datetime.now.ticks is not based on the clock you see in the system tray. The datetime.now.ticks is derived from the CPU clock internal.

Michael Eakins 2010-10-02 15:52:14

I don't know where you're getting your information. Go look at the source code for DateTime.Ticks.get. It returns InternalTicks.get which returns the same field that all the other portions of time are stored. That field is the number of milliseconds since.. whatever the date is, I can't remember. That value comes from the real-time clock on the motherboard.

Tergiver 2010-10-02 17:52:17

EXACTLY! From the mother board(CPU) clock.

Michael Eakins 2010-10-02 19:40:05

Yes, but that clock is set either with the BIOS UI or with the "Clock Settings" dialog in Windows. It's set by the user. If the CMOS battery dies, your clock resets. That is the same clock as the one displayed in the system tray.

Tergiver 2010-10-02 21:11:50

You cannot change the Bios clock through the Windows interface.

Michael Eakins 2010-10-03 01:00:03

Check out these links, they explain how to change your Bios clock and yet they never mention simply using the windows clock setting (1) http://www.computing.net/answers/windows-xp/change-bios-clock-time/70846.html (2) http://blogs.msdn.com/b/oldnewthing/archive/2004/09/02/224672.aspx (3) http://www.pcbuyerbeware.co.uk/BIOS.htm In fact link (2) states that you haven't been able to manipulate the Bios clock through Windows since 3.0 or so.

Michael Eakins 2010-10-03 01:04:11

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Generate Unique ID following a specific pattern like "digitStringDigit" in C#

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