3v4l.org

run code in 150+ php & hhvm versions
Bugs & Features
<?php $i = 1; for($f = 0; $f <= 20; $f++) { echo "F".$i." = ".($i+$f)."\n"; $i++; }
based on E1pFi
Output for 4.3.0 - 7.1.0
F1 = 1 F2 = 3 F3 = 5 F4 = 7 F5 = 9 F6 = 11 F7 = 13 F8 = 15 F9 = 17 F10 = 19 F11 = 21 F12 = 23 F13 = 25 F14 = 27 F15 = 29 F16 = 31 F17 = 33 F18 = 35 F19 = 37 F20 = 39 F21 = 41