3v4l.org

run code in 300+ PHP versions simultaneously
<?php function call_debug_backtrace() { $bt = debug_backtrace(); $bt[1]["args"][0] = "altered"; } function foo(&$a) { var_dump($a); call_debug_backtrace(); var_dump($a); } $a = 1; foo($a);
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(1) int(1)
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, 5.5.0 - 5.5.38, 5.6.0 - 5.6.38, 7.0.0 - 7.0.32, 7.1.0 - 7.1.24, 7.2.0 - 7.2.33, 7.3.16 - 7.3.33, 7.4.0 - 7.4.33
int(1) string(7) "altered"
preferences:
272.54 ms | 404 KiB | 418 Q