When I run this code, all I get is this warning:

> 674562.pl foo
foo in /tmp/*.pl:
Use of uninitialized value in pattern match (m//) at 674562.pl line 26
+.
[download]

Line 26 is:

                if ($this =~ /$bit/) {
[download]

Since your documentation is a little unclear, I am not sure what this code should do. My guess is that you want to imitate the unix grep command, except that you want a count of all occurances of your regexp, rather than a count of all the lines on which the regexp occurs. If that is the case, I think $this = do {local $/; <PL>}; if ($this =~ /$bit/) should not be inside the while loop. The entire file's contents are slurped into $this when you unset the input record separator, $/.

Update: copy'n'pasted the wrong code. Thanks my_nihilist.

Did you test this code yourself?

I have some other critiques:

• Use meaningful variable names. These do not convey much meaning: %hash, $c, $this, $bit
• Always check the success of open and opendir.
• There is no need for these quotes: "$dir"
• Make better use of whitespace for clarity:

      my @rank = sort {$hash{$b} <=> $hash{$a}} keys %hash;
  [download]

Many of these guidelines can be found in the book Perl Best Practices. It is a good investment.

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