File handling (.conf file) in perl

Question

I need to read this .conf file. This file cannot be read by any module such as Config::Tiny, Config::INI, Config::Simple and etc.

Here is the .conf file, let's say the file name is conference.conf :

[ConferenceId] #section
1000 #value
2000
3000
4000

[RadioExt]
1000=102 #parameter and value
2000=202
3000=302
4000=402

What i want is that the perl read the value only and not the section and print it out to the user. I'm still new at perl. I just learned perl for a week. This type of task make me harder to have any progress in reading, writing, appending on configuration file.

What i also want is that the value in [ConferenceId] declared as global. As the value in the [ConferenceId] changed, the other parameters in [RadioExt] also changed. For example,

[ConferenceId]
1100 #the values has been changed
2100
3100
4100

[RadioExt]
1100=102 #parameters also changed
2100=202
3100=302
4100=402

Can anybody help me with this? I know it is such a big favor. But i really needed this so that i can learn more about reading, writing and appending configuration file. Thanks.

Answer 1

The real answer to this is to use Config::Tiny.

However, since this is an learning exercise assigned by your teacher, I will point you at all of the perlfaq5: How do I change, delete, or insert a line in a file, or append to the beginning of a file?. That should demonstrate all of the standard ways to manipulate a file.

If it wasn't also a module, I'd recommend using the core library Tie::File for this problem, but that's probably not your teachers intent.

So my final recommendation is to take a look at the source for Config::Tiny. It's likely to be outside of your skill set, but ideally you would be able to read this entire file by the end of your course. And this problem does not take a complicated bit of code. Looking at how others have solved problems can be oen of the best ways to learn, especially if you're able to recognize which are the better modules.

---

Update

Config::Tiny alone will not be able to a parse your file, because it's not a strict ini file format. The fact that one of your sections has raw values without keys won't work with any of the standard modules.

Below is an example of how to parse your file using regular expressions. Probably should be enhanced with additional error checking to make sure key/value pairs aren't mixed with array values, but this should get you started:

use strict;
use warnings;

my %hash;
my $section;

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

    # Begin Section
    if (/^\s*\[(.*)\]\s*$/) {
        $section = $1;

    # Hash Key & Value
    } elsif (/^(.*?)=(.*)/) {
        $hash{$section}{$1} = $2;

    # Array
    } else {
        push @{$hash{$section}}, $_;
    }
}

use Data::Dump;
dd \%hash;

__DATA__
[ConferenceId]
1000
2000
3000
4000

[RadioExt]
1000=102
2000=202
3000=302
4000=402

Outputs:

{
  ConferenceId => [1000, 2000, 3000, 4000],
  RadioExt     => { 1000 => 102, 2000 => 202, 3000 => 302, 4000 => 402 },
}

Answer 2

Even though the file extension is .conf you should be able to read it like any other text file.

you can try this

$file = "<yourfilename here>";
open(FH,$file);

while(<FH>)
{
$line = $_;
# here you can write your logic 
}