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<?php $x = array ( 0 => array ( 81 => 'assess', ), 1 => array ( 9 => 'assess', ), 2 => array ( 45 => 'assess', ), 3 => array ( 22 => 'assess', ), 4 => array ( 83 => 'assess3', ), 5 => array ( 9 => 'assess', ), ); print_r(array_unique($x, SORT_REGULAR));
Output for 7.0.0 - 7.0.33, 7.1.0 - 7.1.33, 7.2.0 - 7.2.34, 7.3.0 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.33, 8.2.0 - 8.2.29, 8.3.0 - 8.3.25, 8.4.1 - 8.4.12
Array ( [0] => Array ( [81] => assess ) [1] => Array ( [9] => assess ) [2] => Array ( [45] => assess ) [3] => Array ( [22] => assess ) [4] => Array ( [83] => assess3 ) )
Output for 5.4.0 - 5.4.45, 5.5.0 - 5.5.38, 5.6.0 - 5.6.40
Array ( [0] => Array ( [81] => assess ) [1] => Array ( [9] => assess ) [2] => Array ( [45] => assess ) [3] => Array ( [22] => assess ) [4] => Array ( [83] => assess3 ) [5] => Array ( [9] => assess ) )

preferences:
146.48 ms | 409 KiB | 5 Q