3v4l.org

run code in 300+ PHP versions simultaneously
<?php $a1 = array('a1','a2','a3','a4'); $result=implode("",$a1)."<br/>"; echo $result;
Output for 5.3.0 - 5.3.29, 5.4.0 - 5.4.45, 5.5.0 - 5.5.38, 5.6.0 - 5.6.28, 7.0.0 - 7.0.20, 7.1.0 - 7.1.33, 7.2.17 - 7.2.33, 7.3.0 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.27, 8.2.0 - 8.2.17, 8.3.0 - 8.3.4
a1a2a3a4<br/>

preferences:
219.44 ms | 404 KiB | 325 Q