#12 Program suddenly eats CPU resources for particular regex

[Anonymous]

CONTEXT:
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When I noticed this possible bug, I was/am in the middle of creating a regex, therefore it is not completed.

I have a regex like the following:

^(((.*/)+)|(.*\.(html?|php3?|asp)))\"

It is actually part of an AWK script in UNIX that deals with web page links essentially. The regex is used to filter on input like the following:

index.html" title="some other attribute">go to the home page
images/logo.gif" alt="Logo" />

The top is from a html <a href...> tag and the second is from a <img src=...> tag.

The BUG (maybe):
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Now in regex builder when I change my regex from:
^(((.*/)+)|(.*\.(html?|php3?|asp)))\"
To:
^(((.*/?)+)|(.*\.(html?|php3?|asp)))\"

(only the ? was added)
it eats up the computer resources for a few seconds while it thinks about it.
Now I know this may be simply due to the fact that the first half of the regex
(on the left of the |) essentially allows anything (since it says I want 1 or more
of something that may actually be nothing: (.*/?)+ )
i.e.
(.*/?) <---- this is free to match anything, including the empty string
(.*/?)+ <---- therefore this matches one or more of something that could be the empty string...which is the empty string (I suppose)

I don't know whether this is really a bug or is just because the regex is slightly odd and simply requires more thinking time.