Hi all,

In the code below, I pass a hash reference "hashref" to a sub (pass1). This sub localises (using "my") the hashref and changes the values of num1 and num2.

I am curious why changing the values of num1 and num2 inside pass1 affects the values of num1 and num2 in hashref.

How do I preserve the values of hashref whilst making changes in pass1?

my $hashref = {
    num1 => 1,
    num2 => 2

};

print "before pass1: $hashref->{num1}\n"; #prints 1

pass1({ params => $hashref });

print "after pass1: $hashref->{num1}\n"; #prints 2 but would like it t
+o stay as 1

sub pass1 {
    my $self = shift;
    my $params = $self->{params};

    foreach my $key (keys %{ $params }) {
        $params->{$key}++;
    }
    print "Inside pass1...\n";
    print "$params->{num1}\n"; # prints 2 correct
    print "$params->{num2}\n"; # prints 3 correct
}

[download]

Am I missing something obvious?

In reply to How to preserve values outside a sub by Anonymous Monk

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