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<?php $data =[1, 63, 1, 2, 2, 'a', 'b', '1', 'b']; $data = array_filter($data, function ($value) use ($data) { return !(array_count_values($data)[$value] > 1); }); print_r($data);
Output for 5.6.0 - 5.6.40, 7.0.0 - 7.0.33, 7.1.0 - 7.1.33, 7.2.0 - 7.2.33, 7.3.0 - 7.3.30, 7.4.0 - 7.4.23, 8.0.0 - 8.0.11, 8.1rc1 - rc2
Array ( [1] => 63 [5] => a )

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