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How to prevent metacharacter interpolation

by Anonymous Monk
on Mar 14, 2001 at 15:15 UTC ( #64358=categorized question: print w/replies, xml ) Need Help??
Contributed by Anonymous Monk on Mar 14, 2001 at 15:15 UTC
Q&A  > strings


Description:

I want to use pattern-matching operators with the pattern stored in a variable, e.g. m/$pattern/, s/$pattern/$replacement/. The problem is that the patterns may include characters (like brackets) which are special in regular expressions, thus causing an undesired result. What would be the best way to handle this problem?

Answer: How to prevent metacharacter interpolation
contributed by jmcnamara

Use either the quotemeta function: 

    $pattern = quotemeta( $pattern );
    m/$pattern/;

[download]
or use the \Q and \E escape characters: 
    m/\Q$pattern\E/;

[download]
They do exactly the same thing; just one is a function and the other works inside regex patterns.
Answer: How to prevent metacharacter interpolation
contributed by lhoward

If you're just looking to search or search/replace a string and you don't need any special regular expression (regex) capabilities, you could use index or index+substr instead of m// or s///.

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