Regular Expressions 101

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\[([^\[\]]++|(?R))*+\]
/
\[ matches the character [ with index 9110 (5B16 or 1338) literally (case sensitive)
1st Capturing Group
([^\[\]]++|(?R))*+
*+ matches the previous token between zero and unlimited times, as many times as possible, without giving back (possessive)
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
[^\[\]]++
Match a single character not present in the list below
[^\[\]]
++ matches the previous token between one and unlimited times, as many times as possible, without giving back (possessive)
\[ matches the character [ with index 9110 (5B16 or 1338) literally (case sensitive)
\] matches the character ] with index 9310 (5D16 or 1358) literally (case sensitive)
2nd Alternative
(?R)
(?R) recurses the entire pattern
\] matches the character ] with index 9310 (5D16 or 1358) literally (case sensitive)
Your regular expression does not match the subject string.Try launching the debugger to find out why.

Regular Expression
No Match

/
/

Test String

Substitution

Processing...