Regular Expressions 101

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/
((?<=\.)|\s*^)\s*(I )?hope (it|this|that)( will\b| can\b)? helps?( (you|someone(?:\h*else)?)\b)?(:-?\)|🙂️|[!.;,\s])*?(\s*(cheers|good ?luck)([!,.]*))?$
/
gmi
1st Capturing Group
((?<=\.)|\s*^)
1st Alternative
(?<=\.)
Positive Lookbehind
(?<=\.)
Assert that the Regex below matches
\. matches the character . with index 4610 (2E16 or 568) literally (case insensitive)
2nd Alternative
\s*^
\s
matches any whitespace character (equivalent to [\r\n\t\f\v ])
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
^ asserts position at start of a line
\s
matches any whitespace character (equivalent to [\r\n\t\f\v ])
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
2nd Capturing Group
(I )?
? matches the previous token between zero and one times, as many times as possible, giving back as needed (greedy)
I
matches the characters I literally (case insensitive)
hope
matches the characters hope literally (case insensitive)
3rd Capturing Group
(it|this|that)
1st Alternative
it
it
matches the characters it literally (case insensitive)
2nd Alternative
this
this
matches the characters this literally (case insensitive)
3rd Alternative
that
that
matches the characters that literally (case insensitive)
4th Capturing Group
( will\b| can\b)?
? matches the previous token between zero and one times, as many times as possible, giving back as needed (greedy)
1st Alternative
will\b
will
matches the characters will literally (case insensitive)
\b assert position at a word boundary: (^\w|\w$|\W\w|\w\W)
2nd Alternative
can\b
can
matches the characters can literally (case insensitive)
\b assert position at a word boundary: (^\w|\w$|\W\w|\w\W)
help
matches the characters help literally (case insensitive)
s
matches the character s with index 11510 (7316 or 1638) literally (case insensitive)
5th Capturing Group
( (you|someone(?:\h*else)?)\b)?
? matches the previous token between zero and one times, as many times as possible, giving back as needed (greedy)
matches the character with index 3210 (2016 or 408) literally (case insensitive)
6th Capturing Group
(you|someone(?:\h*else)?)
1st Alternative
you
you
matches the characters you literally (case insensitive)
2nd Alternative
someone(?:\h*else)?
someone
matches the characters someone literally (case insensitive)
Non-capturing group
(?:\h*else)?
? matches the previous token between zero and one times, as many times as possible, giving back as needed (greedy)
\h
matches any horizontal whitespace character (equivalent to [[:blank:]])
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
else
matches the characters else literally (case insensitive)
\b assert position at a word boundary: (^\w|\w$|\W\w|\w\W)
7th Capturing Group
(:-?\)|🙂️|[!.;,\s])*?
*? matches the previous token between zero and unlimited times, as few times as possible, expanding as needed (lazy)
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
1st Alternative
:-?\)
: matches the character : with index 5810 (3A16 or 728) literally (case insensitive)
-
matches the character - with index 4510 (2D16 or 558) literally (case insensitive)
\) matches the character ) with index 4110 (2916 or 518) literally (case insensitive)
2nd Alternative
🙂️
🙂️
matches the characters 🙂️ literally (case insensitive)
3rd Alternative
[!.;,\s]
8th Capturing Group
(\s*(cheers|good ?luck)([!,.]*))?
? matches the previous token between zero and one times, as many times as possible, giving back as needed (greedy)
\s
matches any whitespace character (equivalent to [\r\n\t\f\v ])
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
9th Capturing Group
(cheers|good ?luck)
10th Capturing Group
([!,.]*)
$ 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)
i modifier: insensitive. Case insensitive match (ignores case of [a-zA-Z])
Your regular expression does not match the subject string.Try launching the debugger to find out why.

Regular Expression
No Match

/
/
gmi

Test String

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