3v4l.org

run code in 300+ PHP versions simultaneously
<?php var_export( preg_replace('~(?|\d{2}(?=\d{9}$)|\d{3}(?!$))\K~', ' ', '90000800123987') );

Generated using Vulcan Logic Dumper, using php 8.0.0


preferences:
103.41 ms | 1350 KiB | 4 Q