Parse number in BBCode

Question

I have a BBCode quote tag that is formatted like this:

[quote=Username;123456]

The delimiter is always there. How can I only match the digits with a regular expression (PHP)?

Answer 1

One way (among others):

\[[^\d\[\]]+(\d+)\]

See a demo on regex101.com.

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Broken down, this says:

\[         # match an open bracket
[^\d\[\]]+ # match anything not brackets or digits
(\d+)      # capture digits to group $1
\]         # match a closing bracket

Your digits will be in group $1.