I'm searching for UUIDs in blocks of text using a regex. Currently I'm relying on the assumption that all UUIDs will follow a patttern of 8-4-4-4-12 hexadecimal digits.
Can anyone think of a use case where this assumption would be invalid and would cause me to miss some UUIDs?
419 Answers
The regex for uuid is:
[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12} If you want to enforce the full string to match this regex, you will sometimes (your matcher API may have a method) need to surround above expression with ^...$, that is
^[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}$ @ivelin: UUID can have capitals. So you'll either need to toLowerCase() the string or use:
[a-fA-F0-9]{8}-[a-fA-F0-9]{4}-[a-fA-F0-9]{4}-[a-fA-F0-9]{4}-[a-fA-F0-9]{12}
Would have just commented this but not enough rep :)
3Version 4 UUIDs have the form xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx where x is any hexadecimal digit and y is one of 8, 9, A, or B. e.g. f47ac10b-58cc-4372-a567-0e02b2c3d479.
Therefore, this is technically more correct:
/[a-f0-9]{8}-[a-f0-9]{4}-4[a-f0-9]{3}-[89aAbB][a-f0-9]{3}-[a-f0-9]{12}/ If you want to check or validate a specific UUID version, here are the corresponding regexes.
Note that the only difference is the version number, which is explained in
4.1.3. Versionchapter of UUID 4122 RFC.
The version number is the first character of the third group : [VERSION_NUMBER][0-9A-F]{3} :
UUID v1 :
/^[0-9A-F]{8}-[0-9A-F]{4}-[1][0-9A-F]{3}-[89AB][0-9A-F]{3}-[0-9A-F]{12}$/iUUID v2 :
/^[0-9A-F]{8}-[0-9A-F]{4}-[2][0-9A-F]{3}-[89AB][0-9A-F]{3}-[0-9A-F]{12}$/iUUID v3 :
/^[0-9A-F]{8}-[0-9A-F]{4}-[3][0-9A-F]{3}-[89AB][0-9A-F]{3}-[0-9A-F]{12}$/iUUID v4 :
/^[0-9A-F]{8}-[0-9A-F]{4}-[4][0-9A-F]{3}-[89AB][0-9A-F]{3}-[0-9A-F]{12}$/iUUID v5 :
/^[0-9A-F]{8}-[0-9A-F]{4}-[5][0-9A-F]{3}-[89AB][0-9A-F]{3}-[0-9A-F]{12}$/i
I agree that by definition your regex does not miss any UUID. However it may be useful to note that if you are searching especially for Microsoft's Globally Unique Identifiers (GUIDs), there are five equivalent string representations for a GUID:
"ca761232ed4211cebacd00aa0057b223" "CA761232-ED42-11CE-BACD-00AA0057B223" "{CA761232-ED42-11CE-BACD-00AA0057B223}" "(CA761232-ED42-11CE-BACD-00AA0057B223)" "{0xCA761232, 0xED42, 0x11CE, {0xBA, 0xCD, 0x00, 0xAA, 0x00, 0x57, 0xB2, 0x23}}" /^[0-9a-f]{8}-[0-9a-f]{4}-[1-5][0-9a-f]{3}-[89AB][0-9a-f]{3}-[0-9a-f]{12}$/i Gajus' regexp rejects UUID V1-3 and 5, even though they are valid.
2[\w]{8}(-[\w]{4}){3}-[\w]{12} has worked for me in most cases.
Or if you want to be really specific [\w]{8}-[\w]{4}-[\w]{4}-[\w]{4}-[\w]{12}.
In python re, you can span from numberic to upper case alpha. So..
import re test = "01234ABCDEFGHIJKabcdefghijk01234abcdefghijkABCDEFGHIJK" re.compile(r'[0-f]+').findall(test) # Bad: matches all uppercase alpha chars ## ['01234ABCDEFGHIJKabcdef', '01234abcdef', 'ABCDEFGHIJK'] re.compile(r'[0-F]+').findall(test) # Partial: does not match lowercase hex chars ## ['01234ABCDEF', '01234', 'ABCDEF'] re.compile(r'[0-F]+', re.I).findall(test) # Good ## ['01234ABCDEF', 'abcdef', '01234abcdef', 'ABCDEF'] re.compile(r'[0-f]+', re.I).findall(test) # Good ## ['01234ABCDEF', 'abcdef', '01234abcdef', 'ABCDEF'] re.compile(r'[0-Fa-f]+').findall(test) # Good (with uppercase-only magic) ## ['01234ABCDEF', 'abcdef', '01234abcdef', 'ABCDEF'] re.compile(r'[0-9a-fA-F]+').findall(test) # Good (with no magic) ## ['01234ABCDEF', 'abcdef', '01234abcdef', 'ABCDEF'] That makes the simplest Python UUID regex:
re_uuid = re.compile("[0-F]{8}-([0-F]{4}-){3}[0-F]{12}", re.I) I'll leave it as an exercise to the reader to use timeit to compare the performance of these.
Enjoy. Keep it Pythonic™!
NOTE: Those spans will also match :;<=>?@' so, if you suspect that could give you false positives, don't take the shortcut. (Thank you Oliver Aubert for pointing that out in the comments.)
By definition, a UUID is 32 hexadecimal digits, separated in 5 groups by hyphens, just as you have described. You shouldn't miss any with your regular expression.
1const regex = [0-9a-fA-F]{8}\-[0-9a-fA-F]{4}\-[0-9a-fA-F]{4}\-[0-9a-fA-F]{4}\-[0-9a-fA-F]{12} So, I think Richard Bronosky actually has the best answer to date, but I think you can do a bit to make it somewhat simpler (or at least terser):
re_uuid = re.compile(r'[0-9a-f]{8}(?:-[0-9a-f]{4}){3}-[0-9a-f]{12}', re.I) Variant for C++:
#include <regex> // Required include ... // Source string std::wstring srcStr = L"String with GIUD: {4d36e96e-e325-11ce-bfc1-08002be10318} any text"; // Regex and match std::wsmatch match; std::wregex rx(L"(\\{[A-F0-9]{8}-[A-F0-9]{4}-[A-F0-9]{4}-[A-F0-9]{4}-[A-F0-9]{12}\\})", std::regex_constants::icase); // Search std::regex_search(srcStr, match, rx); // Result std::wstring strGUID = match[1]; For UUID generated on OS X with uuidgen, the regex pattern is
[A-F0-9]{8}-[A-F0-9]{4}-4[A-F0-9]{3}-[89AB][A-F0-9]{3}-[A-F0-9]{12} Verify with
uuidgen | grep -E "[A-F0-9]{8}-[A-F0-9]{4}-4[A-F0-9]{3}-[89AB][A-F0-9]{3}-[A-F0-9]{12}" For bash:
grep -E "[a-f0-9]{8}-[a-f0-9]{4}-4[a-f0-9]{3}-[89aAbB][a-f0-9]{3}-[a-f0-9]{12}" For example:
$> echo "f2575e6a-9bce-49e7-ae7c-bff6b555bda4" | grep -E "[a-f0-9]{8}-[a-f0-9]{4}-4[a-f0-9]{3}-[89aAbB][a-f0-9]{3}-[a-f0-9]{12}" f2575e6a-9bce-49e7-ae7c-bff6b555bda4 $UUID_RE = join '-', map { "[0-9a-f]{$_}" } 8, 4, 4, 4, 12; BTW, allowing only 4 on one of the positions is only valid for UUIDv4. But v4 is not the only UUID version that exists. I have met v1 in my practice as well.
0If using Posix regex (grep -E, MySQL, etc.), this may be easier to read & remember:
[[:xdigit:]]{8}(-[[:xdigit:]]{4}){3}-[[:xdigit:]]{12} Edit: Perl & PCRE flavours also support Posix character classes so this'll work with them. For those, change the (…) to a non-capturing subgroup (?:…).
Wanted to give my contribution, as my regex cover all cases from OP and correctly group all relevant data on the group method (you don't need to post process the string to get each part of the uuid, this regex already get it for you)
([\d\w]{8})-?([\d\w]{4})-?([\d\w]{4})-?([\d\w]{4})-?([\d\w]{12})|[{0x]*([\d\w]{8})[0x, ]{4}([\d\w]{4})[0x, ]{4}([\d\w]{4})[0x, {]{5}([\d\w]{2})[0x, ]{4}([\d\w]{2})[0x, ]{4}([\d\w]{2})[0x, ]{4}([\d\w]{2})[0x, ]{4}([\d\w]{2})[0x, ]{4}([\d\w]{2})[0x, ]{4}([\d\w]{2})[0x, ]{4}([\d\w]{2}) Official uuid library uses following regex:
/^(?:[0-9a-f]{8}-[0-9a-f]{4}-[1-5][0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}|00000000-0000-0000-0000-000000000000)$/i See reference
Generalize one, where underscore is also neglected properly and only alphanumeric values are allowed with the pattern of 8-4-4-4-12.
^[^\W_]{8}(-[^\W_]{4}){4}[^\W_]{8}$
or
^[^\W_]{8}(-[^\W_]{4}){3}-[^\W_]{12}$
both give you the same result, but the last one is more readable. And I would like to recommend the website where one can learn as well as test the Regular expression properly:
