- var_dump: documentation ( source)
- strstr: documentation ( source)
- array_shift: documentation ( source)
- explode: documentation ( source)
<?php
$current_domain = 'exx.text.ru';
$target_domain = 'text.ru';
var_dump(strstr($current_domain, '.' . $target_domain) == '.' . $target_domain);
var_dump(array_shift(explode(".","en.example.com")));