Beefy Boxes and Bandwidth Generously Provided by pair Networks
Keep It Simple, Stupid
 
PerlMonks  

How do I escape meta-characters in a user-defined string?

( #6100=categorized question: print w/ replies, xml ) Need Help??
Contributed by Kozz on Mar 25, 2000 at 00:49 UTC
Q&A  > regular expressions


Description:

In the example below, the results are I found a match: "a" I found a match: "b" There was no match for "a+b" Now, the problem is that the + in the third key of the hash is being interpreted as a description of the regular expression, not as a literal character. If I have a large hash which contains these types of meta-characters in the keys, how do I escape those meta-characters to prevent them being interpreted?
#!/usr/bin/perl my %hash=( 'a', '2', 'b', '5', 'a+b', '7', ); my $string='a+b'; my $key; foreach $key (keys %hash){ if($string=~/$key/){ print "I found a match: \"$key\"\n"; }else{ print "There was no match for \"$key\"\n"; } }

Answer: How do I escape meta-characters in a user-defined string?
contributed by btrott

if($string=~/\Q$key\E/){
Quotes the metacharacters.

Please (register and) log in if you wish to add an answer



  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • Outside of code tags, you may need to use entities for some characters:
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.
  • Log In?
    Username:
    Password:

    What's my password?
    Create A New User
    Chatterbox?
    and the web crawler heard nothing...

    How do I use this? | Other CB clients
    Other Users?
    Others chilling in the Monastery: (6)
    As of 2014-10-25 08:52 GMT
    Sections?
    Information?
    Find Nodes?
    Leftovers?
      Voting Booth?

      For retirement, I am banking on:










      Results (142 votes), past polls