Regular Expressions 101

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/
^[\p{L}0-9\+\-_\!\$\%\&\*\?]+(?:\.[\p{L}0-9\+\-_\'\!\$\%\&\*\?]+)*@(([\p{L}0-9\-]+(?:\.[\p{L}0-9]+)+)|(\[\d{1,3}(\.\d{1,3}){3}\]))$
/
gm
^ asserts position at start of a line
Match a single character present in the list below
[\p{L}0-9\+\-_\!\$\%\&\*\?]
+ matches the previous token between one and unlimited times, as many times as possible, giving back as needed (greedy)
\p{L} matches any kind of letter from any language
0-9 matches a single character in the range between 0 (index 48) and 9 (index 57) (case sensitive)
\+ matches the character + with index 4310 (2B16 or 538) literally (case sensitive)
\- matches the character - with index 4510 (2D16 or 558) literally (case sensitive)
_ matches the character _ with index 9510 (5F16 or 1378) literally (case sensitive)
\! matches the character ! with index 3310 (2116 or 418) literally (case sensitive)
\$ matches the character $ with index 3610 (2416 or 448) literally (case sensitive)
\% matches the character % with index 3710 (2516 or 458) literally (case sensitive)
\& matches the character & with index 3810 (2616 or 468) literally (case sensitive)
\* matches the character * with index 4210 (2A16 or 528) literally (case sensitive)
\? matches the character ? with index 6310 (3F16 or 778) literally (case sensitive)
Non-capturing group
(?:\.[\p{L}0-9\+\-_\'\!\$\%\&\*\?]+)*
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
\. matches the character . with index 4610 (2E16 or 568) literally (case sensitive)
Match a single character present in the list below
[\p{L}0-9\+\-_\'\!\$\%\&\*\?]
+ matches the previous token between one and unlimited times, as many times as possible, giving back as needed (greedy)
\p{L} matches any kind of letter from any language
0-9 matches a single character in the range between 0 (index 48) and 9 (index 57) (case sensitive)
\+ matches the character + with index 4310 (2B16 or 538) literally (case sensitive)
\- matches the character - with index 4510 (2D16 or 558) literally (case sensitive)
_ matches the character _ with index 9510 (5F16 or 1378) literally (case sensitive)
\' matches the character ' with index 3910 (2716 or 478) literally (case sensitive)
\! matches the character ! with index 3310 (2116 or 418) literally (case sensitive)
\$ matches the character $ with index 3610 (2416 or 448) literally (case sensitive)
\% matches the character % with index 3710 (2516 or 458) literally (case sensitive)
\& matches the character & with index 3810 (2616 or 468) literally (case sensitive)
\* matches the character * with index 4210 (2A16 or 528) literally (case sensitive)
\? matches the character ? with index 6310 (3F16 or 778) literally (case sensitive)
@ matches the character @ with index 6410 (4016 or 1008) literally (case sensitive)
1st Capturing Group
(([\p{L}0-9\-]+(?:\.[\p{L}0-9]+)+)|(\[\d{1,3}(\.\d{1,3}){3}\]))
1st Alternative
([\p{L}0-9\-]+(?:\.[\p{L}0-9]+)+)
2nd Capturing Group
([\p{L}0-9\-]+(?:\.[\p{L}0-9]+)+)
Match a single character present in the list below
[\p{L}0-9\-]
+ matches the previous token between one and unlimited times, as many times as possible, giving back as needed (greedy)
\p{L} matches any kind of letter from any language
0-9 matches a single character in the range between 0 (index 48) and 9 (index 57) (case sensitive)
\- matches the character - with index 4510 (2D16 or 558) literally (case sensitive)
Non-capturing group
(?:\.[\p{L}0-9]+)+
+ 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 sensitive)
Match a single character present in the list below
[\p{L}0-9]
+ matches the previous token between one and unlimited times, as many times as possible, giving back as needed (greedy)
\p{L} matches any kind of letter from any language
0-9 matches a single character in the range between 0 (index 48) and 9 (index 57) (case sensitive)
2nd Alternative
(\[\d{1,3}(\.\d{1,3}){3}\])
3rd Capturing Group
(\[\d{1,3}(\.\d{1,3}){3}\])
\[ matches the character [ with index 9110 (5B16 or 1338) literally (case sensitive)
\d
matches a digit (equivalent to [0-9])
{1,3} matches the previous token between 1 and 3 times, as many times as possible, giving back as needed (greedy)
4th Capturing Group
(\.\d{1,3}){3}
{3} matches the previous token exactly 3 times
A repeated capturing group will only capture the last iteration. Put a capturing group around the repeated group to capture all iterations or use a non-capturing group instead if you're not interested in the data
\. matches the character . with index 4610 (2E16 or 568) literally (case sensitive)
\d
matches a digit (equivalent to [0-9])
{1,3} matches the previous token between 1 and 3 times, as many times as possible, giving back as needed (greedy)
\] matches the character ] with index 9310 (5D16 or 1358) literally (case sensitive)
$ asserts position at the end of a line
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.Try launching the debugger to find out why.

Regular Expression
No Match

/
/
gm

Test String