Get Computer Unique ID

This question pops about once or twice a month on EE.

If you want to do it for copy protection -- don't!  Two reasons:

1. This kind of copy protection is easy to break.

2. If a legitimate user upgrades his hardware and your program stops working, you'll get no return business and lots of bad publicity.

[I'm submitting this as a comment so you can delete the question]

With the exception of network cards, there's no PC hardware that's guaranteed to have a unique ID.

There are some quasi-unique values that are relatively easy to obtain.  For instance, you can get a volume serial number (a DWORD based on the date and time the volume was formatted) by calling GetVolumeInformation().

One reasonable was to uniquely identify a PC is to create a GUID (CoCreateGuid) and stash it on the system -- the registry is a good place.  The chance of two GUIDs matching is astronomically remote.

Volume serial number is easy to fake.
With GUID can`t sure to that is same computer. With out LAN card GUID is not similar digit, obtain thah is same machine.

VAM345, Your comment is difficult to understand.

Note that I didn't specify that the volume serial number is guaranteed unique.  It's not.  It is, however, a well-distributed value that is _unlikely_ to change over time.

A GUID is a Globally Unique Identifier.  That means a GUID created on one machine via CoCreateGuid() will never match a GUID created on any other machine ever again, regardless of whether or not the machine has a network card.

Problem is I need to obtain ID every time when I start program ant check that is same mashine.