Regular Expressions 101

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/
^(\w+([-+.]\w+)*@\w+([-.]\w+)*\.([A-Za-z]{2,4})[;])+$
/
i
^ asserts position at start of the string
1st Capturing Group
(\w+([-+.]\w+)*@\w+([-.]\w+)*\.([A-Za-z]{2,4})[;])+
+ matches the previous token between one 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
\w
matches any word character (equivalent to [a-zA-Z0-9_])
+ matches the previous token between one and unlimited times, as many times as possible, giving back as needed (greedy)
2nd Capturing Group
([-+.]\w+)*
* 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
Match a single character present in the list below
[-+.]
- matches the character - with index 4510 (2D16 or 558) literally (case insensitive)
This hyphen is treated literally, which might be confusing for others. Consider escaping it or placing at the start or end of the class!
+.
matches a single character in the list +. (case insensitive)
\w
matches any word character (equivalent to [a-zA-Z0-9_])
+ matches the previous token between one and unlimited times, as many times as possible, giving back as needed (greedy)
@ matches the character @ with index 6410 (4016 or 1008) literally (case insensitive)
\w
matches any word character (equivalent to [a-zA-Z0-9_])
+ matches the previous token between one and unlimited times, as many times as possible, giving back as needed (greedy)
3rd Capturing Group
([-.]\w+)*
* 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
Match a single character present in the list below
[-.]
- matches the character - with index 4510 (2D16 or 558) literally (case insensitive)
This hyphen is treated literally, which might be confusing for others. Consider escaping it or placing at the start or end of the class!
. matches the character . with index 4610 (2E16 or 568) literally (case insensitive)
\w
matches any word character (equivalent to [a-zA-Z0-9_])
+ matches the previous token between one and unlimited times, as many times as possible, giving back as needed (greedy)
\. matches the character . with index 4610 (2E16 or 568) literally (case insensitive)
4th Capturing Group
([A-Za-z]{2,4})
Match a single character present in the list below
[A-Za-z]
{2,4} matches the previous token between 2 and 4 times, as many times as possible, giving back as needed (greedy)
A-Z matches a single character in the range between A (index 65) and Z (index 90) (case insensitive)
a-z matches a single character in the range between a (index 97) and z (index 122) (case insensitive)
Match a single character present in the list below
[;]
; matches the character ; with index 5910 (3B16 or 738) literally (case insensitive)
$ asserts position at the end of the string
Global pattern flags
i modifier: insensitive. Case insensitive match (ignores case of [a-zA-Z])
Your regular expression does not match the subject string.

Regular Expression
No Match

/
/
i

Test String