http://www.perlmonks.org?node_id=858989

suniln has asked for the wisdom of the Perl Monks concerning the following question:

Hi All, I I have following piece of code to fetch intermediate and last node of a string. for e.g the input lines are as follows. C:\abc\dfg C:\abc\dfg\#@$#@$@ $key="C:\abc\dfg"; if( $line =~ /$key\\\S+\\/){ # if this is not end node ($pat)=$line=~/$key\\(\S+)\\/; }else{ # if end node ($last_node)=$line=~/$key\\(.*)/; } What is wrong in this reg exp... Thanks, Sunil
  • Comment on unable to differentiate last word and intermediate word in a sentence

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Re: how insert back slash to a string that has only special characters or mixture of both
by suhailck (Friar) on Sep 06, 2010 at 06:10 UTC 
    perl -le '$_=q{hi! how are you, man.};s/([!@#$%^&(),.}{[\]+-])/\\$1/g;
+print'
hi\! how are you\, man\.

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[d/l]

      The quotemeta function do this.

      $var="!@#$%^&(),.}{[]+-";
print "\n$var";
$var_with_slash=quotemeta($var);
print"\n$var_with_slash";

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[d/l]
      suhailck:

      That may not be (see "Update") what OP sought: "for each special character in..." a string of special chars (only) .

      Emphasis supplied.

      Update Oops. Apologies to suhailck!

      I missed the fact that the title explicitly allows for a "mixture" (and relied on OP's narrative and example). Hence, suhailck's reply is arguably better than the next, since the second, among other things, will convert #$%^ to #0\^ and escape the spaces, if a string of "words" is inserted in the $var

      my $var="!@#$%^&(),.Now is the time}{[]+-";
print "\n$var";
my $var_with_slash=quotemeta($var);
print"\n$var_with_slash";

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      outputs:

      !@#0^&(),.Now is the time}{[]+-
\!\@\#0\^\&\(\)\,\.Now\ is\ the\ time\}\{\[\]\+\-

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