Regular Expressions 101

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  • PCRE2 (PHP >=7.3)
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"
(?P<name>[a-z0-9_-])-(?P<major>[0-9])(\.(?P<minor>[0-9]))?(\.(?P<micro>[0-9]))?(?P<release>(_alpha|_beta))*(?P<status>(_pre|_rc\d|_p\d))(?P<revision>-r\d)*
"
gm
Named Capture Group name
(?P<name>[a-z0-9_-])
Match a single character present in the list below
[a-z0-9_-]
+ matches the previous token between one and unlimited times, as many times as possible, giving back as needed (greedy)
a-z matches a single character in the range between a (index 97) and z (index 122) (case sensitive)
0-9 matches a single character in the range between 0 (index 48) and 9 (index 57) (case sensitive)
_- matches a single character in the list _- (case sensitive)
- matches the character - literally (case sensitive)
Named Capture Group major
(?P<major>[0-9])
Match a single character present in the list below
[0-9]
+ matches the previous token between one and unlimited times, as many times as possible, giving back as needed (greedy)
0-9 matches a single character in the range between 0 (index 48) and 9 (index 57) (case sensitive)
3rd Capturing Group
(\.(?P<minor>[0-9]))?
? matches the previous token between zero and one times, as many times as possible, giving back as needed (greedy)
\. matches the character . literally (case sensitive)
Named Capture Group minor
(?P<minor>[0-9])
Match a single character present in the list below
[0-9]
5th Capturing Group
(\.(?P<micro>[0-9]))?
? matches the previous token between zero and one times, as many times as possible, giving back as needed (greedy)
\. matches the character . literally (case sensitive)
Named Capture Group micro
(?P<micro>[0-9])
Match a single character present in the list below
[0-9]
Named Capture Group release
(?P<release>(_alpha|_beta))*
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
A repeated capturing group will only capture the last iteration. Put a capturing group around the repeated group to capture all iterations or use a non-capturing group instead if you're not interested in the data
8th Capturing Group
(_alpha|_beta)
1st Alternative
_alpha
2nd Alternative
_beta
Named Capture Group status
(?P<status>(_pre|_rc\d|_p\d))
10th Capturing Group
(_pre|_rc\d|_p\d)
1st Alternative
_pre
2nd Alternative
_rc\d
3rd Alternative
_p\d
Named Capture Group revision
(?P<revision>-r\d)*
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
A repeated capturing group will only capture the last iteration. Put a capturing group around the repeated group to capture all iterations or use a non-capturing group instead if you're not interested in the data
-r matches the characters -r literally (case sensitive)
\d
matches a digit (equivalent to [0-9])
Global pattern flags
g modifier: global. All matches (don't return after first match)
m modifier: multi line. Causes ^ and $ to match the begin/end of each line (not only begin/end of string)
Your regular expression does not match the subject string.

Regular Expression
No Match

r"
"
gm

Test String