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All the Perl that's Practical to Extract and Report

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Slice of a hashref - why does this work? 1 Comment More | Login | Reply /

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  • This might not help, but I remember hash slices as follows. First really it's just a hash:

    my $hashref = {a => 1, b => 2, c=> 3};

    # it's just a hash:
    %$hashref;

    Second we do our lookup:

    my @of_interest = qw(a c);

    %$hashref{@of_interest};

    Slices return lists, so we need an @ sign instead of the %:

    @$hashref{@of_interest};

    Which gives us:

    use strict;
    use warnings;

    my $hashref = {a => 1, b => 2, c=> 3};
    my @of_interest = qw(a c);

    print "@$hashref{@of_interest}\n";

    You can go the other direction too. If it were just a regular hash (no reference) you'd write:

    print "@hash{@of_interest}\n";

    Because there's that reference there, you need to add in that $. But this way seems to confuse people more.

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