how to assign data into hash from an input file - perl

Question

I am new to perl.
Inside my input file is :
james1
84012345
aaron5
2332111 42332
2345112 18238
wayne[2]
3505554
Question: I am not sure what is the correct way to get the input and set the name as key and number as values. example "james" is key and "84012345" is the value.
This is my code:
#!/usr/bin/perl -w
use strict;
use warnings;
use Data::Dumper;
my $input= $ARGV[0];
my %hash;
open my $data , '<', $input or die " cannot open file : $_\n";
my #names = split ' ', $data;
my #values = split ' ', $data;
#hash{#names} = #values;
print Dumper \%hash;

Answer 1

I'mma go over your code real quick:
#!/usr/bin/perl -w
-w is not recommended. You should use warnings; instead (which you're already doing, so just remove -w).
use strict;
use warnings;
Very good.
use Data::Dumper;
my $input= $ARGV[0];
OK.
my %hash;
Don't declare variables before you need them. Declare them in the smallest scope possible, usually right before their first use.
open my $data , '<', $input or die " cannot open file : $_\n";
You have a spurious space at the beginning of your error message and $_ is unset at this point. You should include $input (the name of the file that failed to open) and $! (the error reason) instead.
my #names = split ' ', $data;
my #values = split ' ', $data;
Well, this doesn't make sense. $data is a filehandle, not a string. Even if it were a string, this code would assign the same list to both #names and #values.
#hash{#names} = #values;
print Dumper \%hash;
My version (untested):
#!/usr/bin/perl
use strict;
use warnings;
use Data::Dumper;
#ARGV == 1
or die "Usage: $0 FILE\n";
my $file = $ARGV[0];
my %hash;
{
open my $fh, '<', $file or die "$0: can't open $file: $!\n";
local $/ = '';
while (my $paragraph = readline $fh) {
my #words = split ' ', $paragraph;
my $key = shift #words;
$hash{$key} = \#words;
}
}
print Dumper \%hash;
The idea is to set $/ (the input record separator) to "" for the duration of the input loop, which makes readline return whole paragraphs, not lines.
The first (whitespace separated) word of each paragraph is taken to be the key; the remaining words are the values.

Answer 2

You have opened a file with open() and attached the file handle to $data. The regular way of reading data from a file is to loop over each line, like so:
#!/usr/bin/env perl
use strict;
use warnings;
use Data::Dumper;
my $input = $ARGV[0];
my %hash;
open my $data , '<', $input or die " cannot open file : $_\n";
while (my $line = <$data>) {
chomp $line; # Removes extra newlines (\n)
if ($line) { # Checks if line is empty
my ($key, $value) = split ' ', $line;
$hash{$key} = $value;
}
}
print Dumper \%hash;

Answer 3

OK, +1 for using strict and warnings.
First Take a look at the $/ variable for controlling how a file is broken into records when it's read in.
$data is a file handle you need to extract the data from the file, if it's not to big you can load it all into an array, if it's a large file you can loop over each record at a time. See the <> operator in perlop
Looking at you code it appears that you want to end up with the following data structure from your input file
%hash(
james1 =>[
84012345
],
aaron5 => [
2332111,
42332,
2345112,
18238
]
'wayne[2]' => [
3505554,
]
)
See perldsc on how to do that.
All the documentation can be read using the perldoc command which comes with Perl. Running perldoc on its own will give you some tips on how to use it and running perldoc perldoc will give you possibly far more info than you need at the moment.