in reply to How to use \W in Regular Expression?

The substitution part of s/// is not a regular expresssion, so it doesn't make much sense to put \W+ in there.  Just remove it: 

$str =~ s/$query\W+/<em>$query<\/em> /ig;

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Re^2: How to use \W in Regular Expression?
by Sachin (Acolyte) on Dec 30, 2009 at 12:14 UTC
    So could you tell me how to highlight this word "perl" in above program?
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      Not sure what you mean. There's no problem with adding <em>...</em> around the word "perl", it's just the \W+ that's inappropriate in the string to substitute...

      Think of it this way: What concrete characters (and how many) should be substituted from the class of characters that \W stands for?

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        I would like to use \W in the following program to ignore special character(:) after word "perl" in above example. and want to highlight only word "perl". So how can i do it? 
        #!/usr/bin/perl -W
$str = <STDIN>;# suppose $str = "i am perl: a system";
chomp($str);
$query = <STDIN>;# suppose $query = 'perl';
chomp($query);
#$query = "perl";
$str =~ s/$query\W+/<em>$query<\/em> \W+/ig;

print " Value = " . $str;

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