3v4l.org

run code in 500+ PHP versions simultaneously
<?php namespace { const A = 'in \\'; } namespace A { const A = 'in A'; } namespace A\B { const A = 'in A\\B'; } namespace A\B\C { echo A; }
Output for 8.1.0 - 8.1.34, 8.2.0 - 8.2.32, 8.3.0 - 8.3.32, 8.4.1 - 8.4.23, 8.5.0 - 8.5.8
in \

preferences:
66.03 ms | 1026 KiB | 4 Q