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in reply to Detecting duplicate keywords passed in a form

Use the uniqueness property of a hash to filter duplicates.

my @keywords = keys %{{ map { lc, undef } qw(this that other foo this bar)}} ;

Updated I changed $_ => undef to lc, undef to be correctly case-insensitive

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Re: Re: Detecting duplicate keywords passed in a form
by flounder99 (Friar) on Mar 21, 2003 at 16:36 UTC
    diotalevi's method looses the order. This maintains the order. 
    my @keywords;
{ #closure so %temphash gets garbage collected
    my %temphash;
    foreach ( map {lc} qw(this that other foo THIS bar)) {
        next if exists $temphash{$_};
        $temphash{$_} = undef;
        push @keywords, $_;
    }
}
print join " ", @keywords;

___OUTPUT____
this that other foo bar

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    flounder

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