3v4l.org

run code in 150+ php & hhvm versions
Bugs & Features
<?php $i = 0; for($f = 0; $f <= 20; $f++) { echo "F".$i." = ".($i+$f)."\n"; $i++; }
based on bNdAh
Output for 4.3.0 - 5.6.28, hhvm-3.10.0 - 3.13.2, 7.0.0 - 7.1.0
F0 = 0 F1 = 2 F2 = 4 F3 = 6 F4 = 8 F5 = 10 F6 = 12 F7 = 14 F8 = 16 F9 = 18 F10 = 20 F11 = 22 F12 = 24 F13 = 26 F14 = 28 F15 = 30 F16 = 32 F17 = 34 F18 = 36 F19 = 38 F20 = 40