3v4l.org

run code in 300+ PHP versions simultaneously
<?php $i = 1; for($f = 0; $f <= 20; $f++) { echo "F".$i." = ".($i+$f)."\n"; $i++; }
Output for 4.3.0 - 4.3.11, 4.4.0 - 4.4.9, 5.0.0 - 5.0.5, 5.1.0 - 5.1.6, 5.2.0 - 5.2.17, 5.3.0 - 5.3.29, 5.4.0 - 5.4.45, 5.5.24 - 5.5.35, 5.6.7 - 5.6.28, 7.0.0 - 7.0.20, 7.1.0 - 7.1.25, 7.2.0 - 7.2.33, 7.3.0 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.28, 8.2.0 - 8.2.18, 8.3.0 - 8.3.6
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
preferences:
213.47 ms | 406 KiB | 328 Q