cant get array of hashes in perl - perl

Question

I have the Employees CSV Data and i
try to insert each employee hash in to an array
open($empOutFh,">empOut.txt")
$hash= [];
while(<$empFh>) {
#columnNames = split /,/, $_ if $.==1;
#columnValues = split /,/, $_;
%row = map{$_=>shift #columnValues}#columnNames;
push #$hash,\%row;
}
print Dumper($hash);
I am getting the output has
$VAR1 = [
{
'emp_no' => '11000',
'hire_date
' => '1988-08-20
',
'birth_date' => '1960-09-12',
'gender' => 'M',
'last_name' => 'Bonifati',
'first_name' => 'Alain'
},
$VAR1->[0],
$VAR1->[0],
$VAR1->[0]
]
But when i am try to print each row it showing different row hash for each time

Answer 1

The problem is that you're using a single hash %row, so \%row is always referring to the same hash. Every time you assign to %row, you're not setting it to a new hash, you're just clearing out the same hash and repopulating it (thereby affecting, indirectly, every element of your array).
To fix this, you need to create a new hash in each loop iteration. The minimal change to your code would be to declare %row as a lexical variable with local scope, by using the my operator:
my %row = map { $_ => shift #columnValues } #columnNames;
push #$hash, \%row;
Another option is to eliminate the intermediate variable entirely, and just generate a reference to a new anonymous hash on each pass:
push #$hash, { map { $_ => shift #columnValues } #columnNames };

Answer 2

If you can't get a map to work properly, use a foreach loop instead. Being able to maintain the code is more important than being clever.
#!/usr/bin/env perl
use strict;
use warnings;
# --------------------------------------
use Data::Dumper;
# Make Data::Dumper pretty
$Data::Dumper::Sortkeys = 1;
$Data::Dumper::Indent = 1;
# Set maximum depth for Data::Dumper, zero means unlimited
local $Data::Dumper::Maxdepth = 0;
# --------------------------------------
# open($empOutFh,">empOut.txt")
my $emp_file = 'empOut.txt';
open my $emp_out_fh, '>', $emp_file or die "could not open $emp_file: $!\n";
# $hash= [];
my #emps = ();
my #columnNames = ();
# while(<$empFh>) {
while( my $line = <$empFh> ){
chomp;
# #columnNames = split /,/, $_ if $.==1;
if( $. == 1 ){
#columnNames = split /,/, $line;
next;
}
# #columnValues = split /,/, $_;
my #columnValues = split /,/, $line;
my %row = ();
# %row = map{$_=>shift #columnValues}#columnNames;
for my $i ( 0 .. $#columnNames ){
$row{$columnNames[$i]} = $columnValues[$i];
}
# push #$hash,\%row;
push #emps, \%row;
# }
}
# print Dumper($hash);
print Dumper \#emps;