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<?php $array = [ ["name" => "Gus", "age" => 32], ["name" => "Jon", "age" => 44], ["name" => "Bob", "age" => 32], ["name" => "Jim", "age" => 103], ["name" => "Ted", "age" => 19], ["name" => "Ben", "age" => 32], ]; foreach ($array as &$row) { $row['order'] = &$ref[$row['age']]; } var_export($array);
Output for 7.4.0 - 7.4.33, 8.0.1 - 8.0.30, 8.1.0 - 8.1.28, 8.2.0 - 8.2.19, 8.3.0 - 8.3.7
array ( 0 => array ( 'name' => 'Gus', 'age' => 32, 'order' => NULL, ), 1 => array ( 'name' => 'Jon', 'age' => 44, 'order' => NULL, ), 2 => array ( 'name' => 'Bob', 'age' => 32, 'order' => NULL, ), 3 => array ( 'name' => 'Jim', 'age' => 103, 'order' => NULL, ), 4 => array ( 'name' => 'Ted', 'age' => 19, 'order' => NULL, ), 5 => array ( 'name' => 'Ben', 'age' => 32, 'order' => NULL, ), )

preferences:
120.13 ms | 403 KiB | 123 Q