A,01,Newton,Issac,Physics, 5.6      
B,144.56                            
B,1034.65                           
B,12.23                             
A,34,Einstein,Albert,Physics,12.22  
B,2346.89                           
B,876.23                            
B,7656.81                           
B,745.21                            
B,25.63                             
B,89.56                             
B,7789.23                           

##</code><code>##

%accounts = ( 
’78’ => { 
’surname’ => ’Feynman’, 
’firstname’ => ’Richard’, 
’job’ => ’Physics’, 
’balance’ => -17.34, 
’transactions => [ 7412.36, 2589.35, 95.32, 12.85, 789.68 ], 
}, 
’89’ => { 
’surname’ => ’Merx’, 
... 
}, 

##</code><code>##

#!/usr/bin/perl
use warnings;
use strict;
use Data::Dumper;

my ( $number, %accounts );
while ( <DATA> ) {
    chomp;
    if ( /^A,/ ) {
        ( undef, $number, my @fields ) = split /,/, $_, -1;
        @{ $accounts{ $number } }{ qw/ surname firstname job balance /
+ } = @fields;
        }
    elsif ( /^B,/ ) {
        my $transaction = ( split /,/ )[ 1 ];
        push @{ $accounts{ $number }{ transactions } }, $transaction;
        }
    }


my $account_hash = $accounts->{78};

foreach my $transactions ($account_hash){
    
        push @{ $account_hash{ transactions } }, '-42.37';
    }

print Dumper $account_hash{ transactions };