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FAQ 6.12 What does it mean that regexes are greedy? How can I get around it?


This is an excerpt from the latest version perlfaq6.pod, which
comes with the standard Perl distribution. These postings aim to
reduce the number of repeated questions as well as allow the community
to review and update the answers. The latest version of the complete
perlfaq is at http://faq.perl.org .

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6.12: What does it mean that regexes are greedy?  How can I get around it?

    Most people mean that greedy regexes match as much as they can.
    Technically speaking, it's actually the quantifiers ("?", "*", "+",
    "{}") that are greedy rather than the whole pattern; Perl prefers local
    greed and immediate gratification to overall greed. To get non-greedy
    versions of the same quantifiers, use ("??", "*?", "+?", "{}?").

    An example:

            $s1 = $s2 = "I am very very cold";
            $s1 =~ s/ve.*y //;      # I am cold
            $s2 =~ s/ve.*?y //;     # I am very cold

    Notice how the second substitution stopped matching as soon as it
    encountered "y ". The "*?" quantifier effectively tells the regular
    expression engine to find a match as quickly as possible and pass
    control on to whatever is next in line, like you would if you were
    playing hot potato.

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so please include as much information as possible and relevant in any
corrections. The perlfaq-workers also don't have access to every
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Working code is greatly appreciated.

If you'd like to help maintain the perlfaq, see the details in
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