3v4l.org

run code in 300+ PHP versions simultaneously
<?php $var1 = 'Hello World'; $var2 = ''; $var2 =& $var1; debug_zval_dump($var1);
Output for 8.1.0 - 8.1.28, 8.2.0 - 8.2.18, 8.3.0 - 8.3.6
string(11) "Hello World" interned
Output for 5.4.0 - 5.4.45, 5.5.0 - 5.5.38, 5.6.0 - 5.6.40, 7.0.0 - 7.0.33, 7.1.0 - 7.1.30, 7.2.0 - 7.2.33, 7.3.0 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30
string(11) "Hello World" refcount(1)
preferences:
255.45 ms | 404 KiB | 360 Q