I would recommend using $seen{$_}++ over $seen{$_}=1 because with the former you have additional information, such as how many times you have seen that particular item. This can be useful for detecting duplicate keys, for example.

As such, these two are perhaps functionally the same in a narrow set of circumstances. Using the ++ approach is much more adaptable, so it should be used in preferance to simple assignment.

In reply to Re^3: using hash uniqueness to find the odd man by tadman
in thread using hash uniqueness to find the odd man by novitiate

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