3v4l.org

run code in 300+ PHP versions simultaneously
<?php $foo = substr("foo",3); if(strlen($foo) == 0){ echo "Run on both PHP 5 and PHP 7\n"; echo gettype($foo); //boolean on PHP 5 and string on PHP 7 }
Output for 7.0.0 - 7.0.33, 7.1.0 - 7.1.33, 7.2.0 - 7.2.33, 7.3.0 - 7.3.33, 7.4.0 - 7.4.29, 8.0.0 - 8.0.19, 8.1.0 - 8.1.6
Run on both PHP 5 and PHP 7 string
Output for 5.6.0 - 5.6.40
Run on both PHP 5 and PHP 7 boolean

preferences:
46.5 ms | 409 KiB | 5 Q