open IN, "d1.txt" or die "No such file:$!\n";
open OUT, ">ABC.txt" or die;
while(<IN>)
{
   chomp $_;
$a[$l]=$_;
++$l;
}
my @array=qw(doxorubicin is a potent anti-estrogen drug and tamoxifen)
+;
for($i=0;$i<$l;++$i)
{
foreach $z(@array)
    {
      if($z=~m/\b\w^$a[$i]$\b/i)
        {
    
        $z=~s/$z/<span style="background-color:yellow;">$z<\/span>/;
        $i++;
    print "@array ";
        
        }
    
    }
    
}

[download]
My script is fine, its just giving range error while matching with terms like below: 
(5r)-6-(4-{[2-(3-Iodobenzyl)-3-Oxocyclohex-1-En-1-Yl]Amino}Phenyl)-5-M
+ethyl-4,5-Dihydropyridazin-3(2h)-One

show range error at 2-(

[download]
Can somebody tell me how to turn off the effect of such characters like brackets, range operator etc

In reply to Invalid range [] by Nandini21

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • 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, details, 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, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            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.