3v4l.org

run code in 300+ PHP versions simultaneously
<?php $xs = array('x'); $ys = array(); foreach ($xs as $idX => $elemX) {} var_dump($idX, $elemX); foreach ($ys as $idY => $elemY) {} var_dump($idY, $elemY);
Output for 8.0.0 - 8.0.30, 8.1.0 - 8.1.28, 8.2.0 - 8.2.18, 8.3.0 - 8.3.6
int(0) string(1) "x" Warning: Undefined variable $idY in /in/5j4Tk on line 10 Warning: Undefined variable $elemY in /in/5j4Tk on line 10 NULL NULL
Output for 5.5.0 - 5.5.35, 5.6.0 - 5.6.28, 7.0.0 - 7.0.20, 7.1.0 - 7.1.20, 7.2.0 - 7.2.33, 7.3.12 - 7.3.31, 7.4.0 - 7.4.25, 7.4.27 - 7.4.33
int(0) string(1) "x" Notice: Undefined variable: idY in /in/5j4Tk on line 10 Notice: Undefined variable: elemY in /in/5j4Tk on line 10 NULL NULL
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, 7.3.32 - 7.3.33, 7.4.26
int(0) string(1) "x" NULL NULL
preferences:
216.52 ms | 403 KiB | 345 Q