Re: Explain the code

This approach is merges the construction of the %seen hash with the extraction of unique elements.

1. reading elements from @array

2. If the current element ($_) and it is not in the hash (%seen), it will push into @result. Then it stored into hash(%seen). As we know hash will not allow duplicate value

Thanks
Gopal

Comment on Re: Explain the code

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Re^2: Explain the code by olus (Curate) on Jul 24, 2008 at 12:58 UTC
`%seen` will also have the number of occurrences of every element of `@a`.	[reply] [d/l] [select]
Re^3: Explain the code by gopalr (Priest) on Jul 24, 2008 at 13:08 UTC
How? If the array (`@a`) has duplicate values, hash will eliminate that.	[reply] [d/l]
Re^4: Explain the code by olus (Curate) on Jul 24, 2008 at 13:12 UTC
Noticed the `++` in `!$seen{$_}++`? `perl -MData::Dumper -e '@a=(1, 2, 1, 2, 3); my @result = grep { !$seen +{$_}++ } @a; print Dumper(\%seen);' $VAR1 = { '1' => 2, '3' => 1, '2' => 2 };` [download]	[reply] [d/l] [select]
Re^4: Explain the code by moritz (Cardinal) on Jul 24, 2008 at 13:09 UTC
The `++` is evaluated for every item in `@a`, grep only checks its return value and picks (or not picks) the element based on that value.	[reply] [d/l] [select]
Re^4: Explain the code by FunkyMonk (Chancellor) on Jul 24, 2008 at 13:11 UTC
`$seen{4} = 3` means that 4 has been seen 3 times. Unless I state otherwise, all my code runs with strict and warnings	[reply] [d/l]

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