Shell Programming and Scripting

 
#!/usr/bin/perl
 
sub addToHash{
  my(%hash) = @_;
 $hash{ 'A' } = 'value';
 $hash{ 'B' } = 'value';
 $hash{ 'C' } = 'value';
 print("Hashmap size is " .keys(%hash) . "\n");
}
 
my %myhash = ();
addToHash(\%myhash);
print("Hashmap size is " .keys(%myhash) . "\n");

Reference found where even-sized list expected at hash.pl line 5.

my ( $href ) = @_;
my %hash = %$hash;

 
#!/usr/bin/perl

sub addToHash{
 my ($href) = @_;
 $href{ 'A' } = 'value';
 $href{ 'B' } = 'value';
 $href{ 'C' } = 'value';
 print("Hashmap size is " .keys(%href) . "\n");
}
 
my %myhash = ();
addToHash(\%myhash);
print("Hashmap size is " .keys(%myhash) . "\n");

#!/usr/bin/perl -w
use strict;
use warnings;

#!/usr/bin/perl

use warnings;
use strict;

sub addToHash {
 my $href = $_[0];
 $href->{ 'A' } = 'value';
 $href->{ 'B' } = 'value';
 $href->{ 'C' } = 'value';
 print "Hashmap size is ". keys( %$href ) . "\n";
}

my %myhash = ();
addToHash \%myhash;
print "Hashmap size is " . keys( %myhash ) . "\n";

$
$
$ cat -n testref.pl
     1  #!perl
     2
     3  sub addToHash{
     4    $href = shift;
     5    ${$href}{'A'} = 'xxx';
     6    ${$href}{'B'} = 'yyy';
     7    ${$href}{'C'} = 'zzz';
     8    print("Hashmap size is " .keys(%{$href}) . "\n");
     9  }
    10
    11  my %myhash = ();
    12  addToHash(\%myhash);
    13  print("Hashmap size is " .keys(%myhash) . "\n");
    14
$
$
$ perl testref.pl
Hashmap size is 3
Hashmap size is 3
$
$
$