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Re^4: Search and Copy

by kennethk (Monsignor)
on Nov 23, 2012 at 17:47 UTC ( #1005308=note: print w/ replies, xml ) Need Help??


in reply to Re^3: Search and Copy
in thread Search and Copy

Again, please use <code> tags and read How do I post a question effectively?

I have found strict to be very helpful to identifying and avoiding bugs in my code -- see Use strict warnings and diagnostics or die. If I were going to write your posted code, it might look more like:

use strict; use warnings; open (my $out, ">", "Results.txt") or die ("Could not open file Result +s.txt; $!"); open (my $in, "<", "Textfile.txt") or die ("Can not open input file: $ +!"); local $/; while (<$in>) { if (/(web site.{250})/i) { print $out $1; } }

Changes that I made include:

  1. I swapped to lexical file handles and 3 argument open, which are considered better practice for a number of reasons. See perlopentut. In particular, this gives strict more power to help and removes the need for explicit close.
  2. I corrected inconsistency between your file name and error message; file names are generally case sensitive.
  3. I swapped to slurp mode using $/. Given the large number of characters you are interested in, it is unlikely they will all fall on the same line.
  4. Your while(<>) loop read data into $_ not $ARG, so I corrected that.
  5. I swapped your regular expression to the regular expression I posted above, with the addition of the s modifier. This makes it so . also matches new lines, and is essential when working in slurp mode.

You may consider going to http://learn.perl.org to gather some learning resources before trying to run too far.


#11929 First ask yourself `How would I do this without a computer?' Then have the computer do it the same way.


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