Would like some efficiency training...
I have two large lists @a and @b...
my goal is to find everything in list @b that is not in list @a, and put it in list @c
currently I do this by: 
foreach my $thing(@b){
    if(scalar grep(/^$thing/,@a) == 0){
        push(@c,$thing);
    }
}

[download]
Is there a better way to do this? For example is there a list comparison function that would work like:
@c = compare(@a,@b); where compare finds everything in @b that is not in @a? maybe it even takes a third parameter that finds eveything that is the same between the two lists.
Thanks

In reply to List Comparison by ketema

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