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Top Forums UNIX for Beginners Questions & Answers Perl/Array Sorting : Can someone please explain below code $h{$_}++ Post 303032307 by Tanu on Friday 15th of March 2019 05:38:28 AM
Old 03-15-2019
Perl/Array Sorting : Can someone please explain below code $h{$_}++

Code:
sub uniq {
    my %h;
    return grep { !$h{$_}++ } @_
}

The above code is to remove duplicates from array.

I am having hard time understanding below things (basically around highlighted code in bold)-

when was the value inserted in hash?
and are we only adding a key in Hash not values?
Code:
$h{$_}++

what "++" means here
 

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COLLATOR_ASORT(3)							 1							 COLLATOR_ASORT(3)

Collator::asort - Sort array maintaining index association

       Object oriented style

SYNOPSIS
public bool Collator::asort (array &$arr, [int $sort_flag]) DESCRIPTION
Procedural style bool collator_asort (Collator $coll, array &$arr, [int $sort_flag]) This function sorts an array such that array indices maintain their correlation with the array elements they are associated with. This is used mainly when sorting associative arrays where the actual element order is significant. Array elements will have sort order according to current locale rules. Equivalent to standard PHP asort(3). PARAMETERS
o $coll -Collator object. o $arr -Array of strings to sort. o $sort_flag - Optional sorting type, one of the following: o Collator::SORT_REGULAR - compare items normally (don't change types) o Collator::SORT_NUMERIC - compare items numerically o Collator::SORT_STRING - compare items as strings Default $sort_flag value is Collator::SORT_REGULAR. It is also used if an invalid $sort_flag value has been specified. RETURN VALUES
Returns TRUE on success or FALSE on failure. EXAMPLES
Example #1 collator_asort(3)example <?php $coll = collator_create( 'en_US' ); $arr = array( 'a' => '100', 'b' => '50', 'c' => '7' ); collator_asort( $coll, $arr, Collator::SORT_NUMERIC ); var_export( $arr ); collator_asort( $coll, $arr, Collator::SORT_STRING ); var_export( $arr ); ?> The above example will output: array ( 'c' => '7', 'b' => '50', 'a' => '100', )array ( 'a' => '100', 'b' => '50', 'c' => '7', ) SEE ALSO
Collator constants, collator_sort(3), collator_sort_with_sort_keys(3). PHP Documentation Group COLLATOR_ASORT(3)
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