<?php for ($i = 2; $i <= 20; $i++) { for ($j = 2; $j*$j <= $i; $j++) if ($i % $j == 0) continue 2; $prime[] = $i; }
Standard input is empty
array(8) { [0]=> int(2) [1]=> int(3) [2]=> int(5) [3]=> int(7) [4]=> int(11) [5]=> int(13) [6]=> int(17) [7]=> int(19) }