format output while writing it to the output file in perl

Question

I'm reading a file and processing according to the need. As the output has tables, few columns are misaligned. I'm using while loop for processing of input read file.

Regexp:

$_ =~ s/$var/$mod{$var}/;
print "$_";

Please suggest me better way to format the output.

col1 (40spaces) col2(nspaces) coln(nspaces)

Here it is how i done it: open(MYFILE,'log') while() { if(condition) my($var) = (split ())[]; $var =~ s/xyz/xy/; if($var = condition) $var = $1; } $_ =~ s/$var/$mod{$var}/; print "$_"

i need the output table 2nd column to be 40 spaces

I'm totally beginner, so this is the first time im using output formatting. As the processing is done on the fly in a while loop and later using $_ for print, is there a way to format the output column ? — user3159355
– user3159355, Commented Jan 9, 2014 at 23:12

tobyink · Accepted Answer · 2014-01-10 09:46:47Z

2

I would suggest rather than using s/// on the whole line, you should split the line into fields, do what you need with each field, then output a formatted line using printf. Something like this:

use strict;
use warnings;

sub trim { $_ = shift; s/(\A\s+)|(\s+\z)//gr }  # or use String::Trim

my %full_country_name = (
  ENG  => 'England',
  SCO  => 'Scotland',
  WAL  => 'Wales',
);

while (<DATA>)
{
  chomp;

  # Input columns are 4 chars, 5 chars, and everything else
  my ($number, $country, $letter) =
    map trim($_),
    m{^ (.{4}) (.{5}) (.+) $}x;

  # Output columns are 4 chars, 10 chars, and everything else
  printf(
    "%-4s%-10s%s\n",
    $number,
    $full_country_name{$country},
    $letter,
  );
}

__DATA__
1   ENG  A
2   SCO  B
3   WAL  C

Update: edited to include an implementation of the trim function.

edited Jan 10, 2014 at 9:46

answered Jan 9, 2014 at 22:43

tobyink

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2 Comments

user3159355 Over a year ago

Im getting error saying can't locate string/trim.pm. is it version issue ?

tobyink Over a year ago

Then install String::Trim, or write a replacement trim function. Something like sub trim { $_ = shift; s/(\A\s+)|(\s+\z)//gr }

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