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Snippet Name: Removing duplicate array items while preserving order

Description: This snippet removes duplicate array items while preserving the array order.
Each string is tested to see if that key already refers to a non-false value. The post-increment operator (++) adds one to that key's value, but only after the condition is checked. The result is that the first time a key string is encountered the condition is false (since the value is undefined) and the key is therefore pushed onto the second array.

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Comment: (none)

Author: CoderZone
Language: PERL
Highlight Mode: PERL
Last Modified: December 03rd, 2010

@arr = qw(one two one three four two four);
foreach (@arr) {
    push(@arr2, $_) unless ($seen{$_}++);
print "@arr2";
# returns 'one two three four'
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