srikdatta:

You were close, but you're getting the error because you haven't done anything to put a value in $_. It appears like you're wanting to scan through a file, so you'd do something like this:

#!/tool/pandora64/bin/perl5.8.8 -w

use strict;
use warnings;

my @verilogfiles = glob '*.verilog';
my ($vf, $of, $i, $j);

print "Define the path for sdf_annotate.v: ";

my $path = <STDIN>;

chomp($path);

#For verilog files
foreach my $b (@verilogfiles)
{
       open $vf, '>>', $b or die "Could not open file '@verilogfiles' 
+$!";
       while (<$vf>) 
       {
           if($_ =~ /module entity\;/)
           {       
               print $vf "\`include \"$path\"\n";
           }
       }
}
close ($vf);

[download]

The while (<$vf>) { loop will load a line from $vf into $_ and execute the loop body, and repeat until there are no more lines in the file.

...roboticus

When your only tool is a hammer, all problems look like your thumb.

In reply to Re: Use of uninitialized value $_ in pattern match (m//) by roboticus
in thread Use of uninitialized value $_ in pattern match (m//) by srikdatta

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.