Read a series and add a value before and after that series.

[Darshan S]

I am very new to perl. Pls do help me out guys.

I have a SAMPLE.txt file with values
300000
295000
280000
300000
300000

I need to read this file and over-write or creat a new file as below

300000
295000
280000
300000

i.e. For values series other than 300000, add 300000 before and after the values as above.

[computerfox]

How's this?

#!/bin/perl
use strict;
use warnings;

sub gen(){
 my $path=shift;
 my $handler;
 my @rows;
 open($handler,"<",$path);
 while(<$handler>){
  my $row=$_;
  chomp($row);
  push(@rows,$row);
 }
 for(my $i=0;$i<$#rows;$i++){
  print $rows[$i]."\n";
  if($i>2){
   if($rows[$i] != "300000" && $rows[-2] != "300000"){
    print "300000\n";
   }
  }
 }
}
sub menu(){
 print "perl gen30.pl {input_file}";
}
if($#ARGV>-1){
 &gen($ARGV[0]);
}
else{
 print "Please provide the path to the input file...";
 print "\n";
 &menu();
}

You would run the script like this:

perl gen30.pl sample.txt > output.txt

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[RonB]

Your description of the desired output is a little vague.

Given this file content:
300000
295000
280000
300000
270000
300000
300000

Should the output be:
300000
295000
280000
300000
300000
270000
300000

or should it be:
300000
295000
280000
300000
270000
300000

#!/usr/bin/perl

use warnings;
use strict;

local $/ = "300000\n";

while (<DATA>) {
    chomp;
    next if /^\s*$/;
    print "$/$_$/";
}

__DATA__
300000
295000
280000
300000
270000
300000
300000

[RonB]

FYI,

  while(<$handler>){
  my $row=$_;
  chomp($row);
  push(@rows,$row);
 }

Could be shortened and better written as:

chomp(my @rows = <$handler>);

And:

for(my $i=0;$i<$#rows;$i++){

is better written as:

for my $i (0 .. $#rows - 1) {

[computerfox]

Well noted Ron.
Thanks.