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run code in 300+ PHP versions simultaneously
<?php $array = ['A', 'A', 'B', 'B', 'C', 'A', 'A']; $result = []; foreach ($array as $v) { if (!isset($ref[$v])) { unset($ref); $ref[$v] = 1; $result[$v][] =& $ref[$v]; } else { ++$ref[$v]; } } var_export($result);
Output for 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 ( 'A' => array ( 0 => 2, 1 => 2, ), 'B' => array ( 0 => 2, ), 'C' => array ( 0 => 1, ), )
preferences:
64.65 ms | 406 KiB | 5 Q