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run code in 150+ php & hhvm versions
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<?php $array1 = array('A', 'B'); $array2 = array('1', '2', '3'); $num = count($array2); //The total number of possible combinations $total = pow(2, $num); $temp = array(); //Loop through each possible combination for ($i = 0; $i < $total; $i++) { //For each combination check if each bit is set for ($j = 0; $j < $num; $j++) { //Is bit $j set in $i? if (pow(2, $j) & $i) $temp[] = $array2[$j] . ' '; } } print_r($temp);
based on ceeOF
Output for 4.3.0 - 7.1.0
Array ( [0] => 1 [1] => 2 [2] => 1 [3] => 2 [4] => 3 [5] => 1 [6] => 3 [7] => 2 [8] => 3 [9] => 1 [10] => 2 [11] => 3 )