how to extract data from a table into a fixed length file

I mean address from 41st position

Hi,

Many thanks for your response. I used that and it works fine. But the problem is, I have over 200 columns in the table and for each column, I have to write sprintf("%10s%-30s%-40s", $id, $name, $address), corresponding to their widths, which becomes very unwieldy and difficult to maintin.

Is there a way to use config file such that I only need to change the config file once(if there is any field width change in any column) and I can generate the file accordingly?

The config file should just have column name and its width.

If you put fields in this format in a file called config.txt:

id,10
name,30
address,40

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You could then do your processing like this:

open CONFIG, "<config.txt" or die "Can't open config file!";
while (<CONFIG>)
{
        chomp;
        ($name, $length) = split(',');
        $format .= "%${length}s";   # This will left-justify all fields
}

# Populate the @values array with the column values of a
# a row of your table.  I'll just hard code it here, but you
# will probably read a record from the table.
@values = (123, 'My Name', 'My Address');

printf($format, @values);

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;

I am getting the output like this

%10 s%30 s123


below is my code

use strict;

my $core_config = "$ENV{'CFG'}/menir-core-config-test.txt";
my $name;
my $length;
my $format;

open CONFIG, "<$core_config" or die "Can't open config file!";
while (<CONFIG>)
{
        chomp;
        ($name, $length) = split(',');
        $format .= "%${length}s";   # This will left-justify all fields
}

my $outfile = "$ENV{'DATA'}/CORE.txt";

my @row = (123, 'My Name', 'My Address');
printf($format, @row);
----------------------------------------------

this is my config ->

id,10
name,30
address,10

Hi Sunny,

Your version of the code works for me.  All I changed was:
    my $core_config = "$ENV{'CFG'}/menir-core-config-test.txt";
to:
    my $core_config = 'config.txt';
so it would work in my environment, and I got this output:

       123                       My Name                              My Address

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Question:
Does my version of the code work for you (if you just copy/paste it from my previous post)?

tel2

Specifying the field width as part of the csv data is ok, but doesn't scale well.

A better approach would be to use an actual config file for the format specification.  There are a number of config modules to choose from on CPAN.  Here's an example using a YAML module/format.

config.yml

fields:  # list of fields in desired order
    - id
    - name
    - address
    - salary

---  # field format specifications
id:
    width: 10
    justify: '-'
    type: d

name:
    width: 30
    type: s

address:
    width: 30
    type: s

salary:
    width: 12
    type: f
    precision: .2

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Test script:

#!/usr/bin/perl

use 5.010;
use strict;
use warnings;
use YAML::Tiny;

my $conf   = YAML::Tiny->read( 'config.yml' );
my $fields = $conf->[0]{fields};
my $format;

foreach my $field ( @$fields ) {
    no warnings 'uninitialized';

    $format .= '%' . $conf->[1]{$field}{justify}
                   . $conf->[1]{$field}{width}
                   . $conf->[1]{$field}{precision}
                   . $conf->[1]{$field}{type};
}

my @row = (123, 'My Name', 'My Address', 12.5);
printf($format, @row);

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Output:
D:\test>sunny82.pl
123                              My Name                    My Address       12.50

Hi,

Sorry for replying a bit late.

@tel2: The output I am getting is "%10 s%30 s       123"

The code is exactly the same as your code, word to word.

Is it because of tis statement ?

$format .= "%${length}s";   # This will left-justify all fields

@FishMonger: @INC does not have YAML::Tiny. Can we use some other module?

Hi Sunny,

"> The code is exactly the same as your code, word to word."
Perhaps, but the code you pasted above is not the same as mine.
Please copy/paste my code to your machine (again), run it, then copy/paste my code and the results here for analysis.

"> Is it because of tis statement ?
> $format .= "%${length}s";   # This will left-justify all fields"
Dunno.  That statement works in my Perl 5.10 Linux environment I'm using, in both your version and my version of my code.

I doubt this is an issue, but what version of Perl are you using?  Type "perl -v" and paste the output here.

Thanks.
tel2

What operating system are you running, Sunny?  I'm assuming UNIX/Linux, below.

Further to my post above, here's an alternative way to write that format line (line #6 in my 2nd post):
    $format .= '%' . $length . 's';
If that doesn't work in my script, please run each of the following one-liners from the Linux command line, and post the command and the output here:
    perl -e '$length=12;$format .= "%${length}s";print $format'

    perl -e '$length=12;$format .= "%" . $length . "s";print $format'

When you copy/paste my code back here for analysis (see my last post for details), please use this UNIX/Linux command to display the code before copying it:
    cat -vet the-script-name-of-my-version-of-the-code.pl
Hopefully that will show if there have been any strange characters inserted during the copy/paste to your system.