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Re: Syntax explanation required

by LanX (Canon)
on Jan 02, 2013 at 12:35 UTC ( #1011259=note: print w/ replies, xml ) Need Help??


in reply to Syntax explanation required

> my @uniq = keys %{ {%hash1, %hash2} };

From inside out:

- First the two hashes are flattened to lists, which are combined to a long list.

- Building a new (anonymous) hashref will eliminate duplicated entries from that hash ╣

- To be able to extract▓ the keys you still need to dereference this ano-hashref with %{..}.

step by step:

DB<111> %hash1= (a=>1,b=>2) => ("a", 1, "b", 2) DB<112> %hash2= (a=>1,c=>3) => ("a", 1, "c", 3) DB<113> (%hash1, %hash2) => ("a", 1, "b", 2, "c", 3, "a", 1) DB<115> + {%hash1, %hash2} => { a => 1, b => 2, c => 3 } DB<117> %{ {%hash1, %hash2} } => ("c", 3, "a", 1, "b", 2) DB<118> keys %{ {%hash1, %hash2} } => ("c", "a", "b")

Cheers Rolf

UPDATES:

╣) because repeated keys will be overwritten.

▓) at least with older perl-versions, see Athanasius' remark


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Re^2: Syntax explanation required
by ghosh123 (Monk) on Jan 02, 2013 at 13:00 UTC
    Wonderful explanation by 'step-by-step'

    Thanks a lot !!!

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