3v4l.org

run code in 300+ PHP versions simultaneously
<?php function a($n){$F='%1$'.($n-1)."s*%1\$s\n";$L='';do printf($F,$n?$L:'');while($n--&&$L.='*');} a(5);

preferences:
16.7 ms | 402 KiB | 5 Q