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What does this regexp mean in Perl?

Posted on 2012-09-11
Medium Priority
Last Modified: 2012-09-14
Can you please tell me what this regexp means?


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I use this to get the files with the extension .cpp

But I am wondering if I need to use ? in this regexp and if yes what it means?
Question by:Tolgar
LVL 28

Accepted Solution

FishMonger earned 1000 total points
ID: 38387227
The . matches any character

The * is a quantifier meaning 0 or more of the preceding match and match as mush as possible (greedy)

The ? makes the preceding match non greedy, match the least amount

The \ escapes the . to match it literally

Mastering Regular Expressions, 3rd Edition
LVL 85

Assisted Solution

ozo earned 1000 total points
ID: 38387291
perl -MYAPE::Regex::Explain -e "print YAPE::Regex::Explain->new(qr/.*?\.cpp/)->explain"
The regular expression:


matches as follows:
NODE                     EXPLANATION
(?-imsx:                 group, but do not capture (case-sensitive)
                         (with ^ and $ matching normally) (with . not
                         matching \n) (matching whitespace and #
  .*?                      any character except \n (0 or more times
                           (matching the least amount possible))
  \.                       '.'
  cpp                      'cpp'
)                        end of grouping

If you had a string like "abc.cppdef.cppghi" then
(.*?\.cpp) would match "abc.cpp"
(.*\.cpp) would match "abc.cppdef.cpp"

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