Is the format of GUID always the same?

Question

GUID you get something like aaaef973-d8ce-4c92-95b4-3635bb2d42d5

Is it always the same? Is it always going to have the following format

8 char "-", 4 char "-", 4 char "-", 4 char "-", 12 char

I'm asking because i need to convert a GUID without "-" to GUID with "-" and vice visa.

score 34 · Accepted Answer · edited Oct 27 '17 at 08:42

34

No; there are other formats, such as the format you listed except with braces. There's also more complex formats. Here are some of the formats MSDN lists:

UUID formats

32 digits: 00000000000000000000000000000000 (N)

32 digits separated by hyphens: 00000000-0000-0000-0000-000000000000 (D)

32 digits separated by hyphens, enclosed in braces: {00000000-0000-0000-0000-000000000000} (B)

32 digits separated by hyphens, enclosed in parentheses: (00000000-0000-0000-0000-000000000000) (P)

Four hexadecimal values enclosed in braces, where the fourth value is a subset of eight hexadecimal values that is also enclosed in braces: {0x00000000,0x0000,0x0000,{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00}} (X)

—MSDN

edited Oct 27 '17 at 08:42

rjv

6,058
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answered Oct 15 '11 at 02:55

icktoofay

126,289
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I'm curious _why_ GUIDs are rendered in groups of 8,4,4,4,12 instead of (for example) 4 groups of 8 - and why the `"X"` format has such a strange format. What's so special about the last 8 bytes that requires them to be rendered differently? – Dai Dec 14 '19 at 02:48
@Dai: See [UUID format: 8-4-4-4-12 - Why?](https://stackoverflow.com/q/10687505) – icktoofay Apr 25 '20 at 21:47
Unrelated to this, how these differ from MD5 hashes? – Rajesh Swarnkar Jan 12 '23 at 05:08

score 4 · Answer 2 · edited May 23 '17 at 11:53

You should simply rely upon it being 32 hexadecimal characters, there can be a variety of ways to present it. Check the Wikipedia article for more information, including a description of how they are commonly written.

For your conversion you should really rely on the static Guid.Parse() methods. Using a mix of your example and the ones in icktoofay's answer, this works nicely:

        var z = Guid.Parse("aaaef973-d8ce-4c92-95b4-3635bb2d42d5");
        z = Guid.Parse("{aaaef973-d8ce-4c92-95b4-3635bb2d42d5}");
        z = Guid.Parse("{0x00000000,0x0000,0x0000,{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00}}");

then for outputting them with or without hyphens etc you can use the Guid.ToString() method with one of the established format codes.

How many characters is it, if it's stored as a string with it's braces ? — Russ Clarke, Oct 15 '11 at 02:57

score 0 · Answer 3 · edited Feb 23 '16 at 12:14

0

Most of the time, GUIDS are 32-character hexadecimal strings such as {21EC2020-3AEA-1069-A2DD-08002B30309D} (unless they're encoded in Base-64), and are usually stored as a 128-bit integers. They won't always have hyphens, though.

edited Feb 23 '16 at 12:14

Liam

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answered Oct 15 '11 at 02:55

lottscarson

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That's not to say that can't be saved in other formats, with or without braces and spaces or hyphens. – Russ Clarke Oct 15 '11 at 02:58

Is the format of GUID always the same?

3 Answers3

UUID formats

Linked