3v4l.org

run code in 300+ PHP versions simultaneously
<?php $v1 = 5; $v2 = '5-4'; $time = microtime(1); $i = 0; while($i++ < 1000000) echo '','','','',''; echo (microtime(1)-$time)." seconds for commas"; echo "\n"; $time = microtime(1); $i = 0; while($i++ < 1000000) echo ''.''.''.''.''; echo (microtime(1)-$time)." seconds for dot";

preferences:
45.41 ms | 402 KiB | 5 Q