in reply to header footer

G'day gupr1980,

Welcome to the monastery.

Your substitution regex has little bearing on the task you describe. You might want to get up to speed on Perl's regular expresions by reading "perlrequick - Perl regular expressions quick start" and "perlretut - Perl regular expressions tutorial".

Having said that, I see no reason to use regular expressions here: substr is quite capable of doing this (and I'd expect it to be a lot faster).

Here's an example script, pm_1076973.pl, with much short header and footer lengths for demo purposes: 

#!/usr/bin/env perl

use strict;
use warnings;

$^I = '.bak';

my $head_len = 5; 
my $foot_len = 3; 

while (<>) {
    chomp;
    print substr($_, $head_len, length($_) - $head_len - $foot_len), "
+\n";
}

[download]

Here's the starting files (before that script is run):

$ ls -l pm_1076973.*
-rwxr-xr-x  1 ken  staff  210  5 Mar 08:50 pm_1076973.pl
-rw-r--r--  1 ken  staff   87  5 Mar 08:46 pm_1076973.txt

[download]
$ cat pm_1076973.txt
12345... content ...123
12345... more content ...123
12345... even more content ...123

[download]

Now run the script:

$ pm_1076973.pl pm_1076973.txt

[download]

Now the files look like this:

$ ls -l pm_1076973.*
-rwxr-xr-x  1 ken  staff  202  5 Mar 08:56 pm_1076973.pl
-rw-r--r--  1 ken  staff   63  5 Mar 08:56 pm_1076973.txt
-rw-r--r--  1 ken  staff   87  5 Mar 08:46 pm_1076973.txt.bak

[download]
$ cat pm_1076973.txt
... content ...
... more content ...
... even more content ...

[download]
$ cat pm_1076973.txt.bak
12345... content ...123
12345... more content ...123
12345... even more content ...123

[download]

-- Ken

Replies are listed 'Best First'.
Re^2: header footer
by gupr1980 (Acolyte) on Mar 04, 2014 at 22:27 UTC
    Does your code assume there is just one header and footer in the file? If not, i am not seeing how it will go from one header/footer segment to another. And thanks for the reading links. It definitely helps.
[reply]
      "Does your code assume there is just one header and footer in the file?"

      No it does not. Furthermore, given I put in a fair amount of effort to show the exact input and output, I'm surprised you're asking.

      "If not, i am not seeing how it will go from one header/footer segment to another."

      That sounds like you didn't even try it. Did you just have a quick look and decided it wouldn't work?

      Changing the lengths from my demo 5 and 3 to your real application requirements of 50 and 30, your sample records (posted below): 

      HDR.S287878877.DDDDD.DDDDDDXXXXXXXXXXXXXXXXXXXXXXX1STR HYTRES NAME PLA
+CE DEST GGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGG GGGGGG
+GGGGGGGGGGGGGG1111111111111111111112222222222222222222222222222333333
+333333333333333333333444444444444444444444444444444444455 55555555555
+55555555555555555566666666666666777777777777FTRDDDDDDDDDDFFFFFFFFFFFF
+FFFFF
HDR.S287878877.DDDDD.DDDDDDXXXXXXXXXXXXXXXXXXXXXXX1STR HYTRES NAME PLA
+CE DEST GGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGG GGGGGG
+GGGGGGGGGGGGGG1111111111111111111112222222222222222222222222222333333
+333333333333333333333444444444444444444444444444444444455 55555555555
+55555555555555555566666666666666777777777777FTRDDDDDDDDDDFFFFFFFFFFFF
+FFFFF

      [download]

      become

      1STR HYTRES NAME PLACE DEST GGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGG
+GGGGGGGGGGGG GGGGGGGGGGGGGGGGGGGG111111111111111111111222222222222222
+222222222222233333333333333333333333333344444444444444444444444444444
+4444455 5555555555555555555555555555566666666666666777777777777
1STR HYTRES NAME PLACE DEST GGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGG
+GGGGGGGGGGGG GGGGGGGGGGGGGGGGGGGG111111111111111111111222222222222222
+222222222222233333333333333333333333333344444444444444444444444444444
+4444455 5555555555555555555555555555566666666666666777777777777

      [download]

      -- Ken

[reply]
[d/l]
[select]
        You are right. I didnt give it a try. It just looked like it did. I will test it. Thanks for your time.
[reply]

In Section Seekers of Perl Wisdom