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Esteemed RegEx-Monkers:

In parsing a log file lines that contains XML-ish content with a single regex, I'm having trouble understanding the subtleties of optional capture.

The string I'm parsing is like:

<blah1 phase="2" type="MyType" more_keys="Values" <Unwanted/> <SomeTa +gIwant><k1="v1"></SomeTagIwant>
And I'm trying to extract the content of the "type", and the tag name of a tag that ends with "TagIwant".
The Tag may or may not be present.

I'm able to capture both pieces with the RE:

\btype="([^"]+)".+<(\w+TagIwant\b)
but - the match fails if I append a "?" to the expression, in an attempt to make it optional.
I.e. this fails:
perl -E '$x=q|<blah1 phase="2" type="MyType" more_keys="Values" <Unwa +nted/> <SomeTagIwant><k1="v1"></SomeTagIwant>|; say for $x=~/\btype +="([^"]+)".+<(\w+TagIwant\b)?/'
Which returns only "MyType", and not the second expected capture of "SomeTagIwant".

The "\b" is an attempt to deal with variations like <SomeTagIwant/> and <SomeTagIwant k3="v3" /> .

I'm hoping for (1) Explanations for why the "?" fails, and (2) Suggestions on how to fix it.

                All power corrupts, but we need electricity.


In reply to Regex Optional capture doesn't by NetWallah

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