Regular Expressions 101

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/
^([\w\.\-]+)@([\w\-]+)((\.(\w){2,3})+)$
/
gm
^ asserts position at start of a line
1st Capturing Group
([\w\.\-]+)
Match a single character present in the list below
[\w\.\-]
+ matches the previous token between one and unlimited times, as many times as possible, giving back as needed (greedy)
\w matches any word character (equivalent to [a-zA-Z0-9_])
\. matches the character . with index 4610 (2E16 or 568) literally (case sensitive)
\- matches the character - with index 4510 (2D16 or 558) literally (case sensitive)
@ matches the character @ with index 6410 (4016 or 1008) literally (case sensitive)
2nd Capturing Group
([\w\-]+)
Match a single character present in the list below
[\w\-]
+ matches the previous token between one and unlimited times, as many times as possible, giving back as needed (greedy)
\w matches any word character (equivalent to [a-zA-Z0-9_])
\- matches the character - with index 4510 (2D16 or 558) literally (case sensitive)
3rd Capturing Group
((\.(\w){2,3})+)
4th Capturing Group
(\.(\w){2,3})+
+ 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
\. matches the character . with index 4610 (2E16 or 568) literally (case sensitive)
5th Capturing Group
(\w){2,3}
{2,3} matches the previous token between 2 and 3 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_])
$ 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