- chr: documentation ( source)
- preg_replace_callback: documentation ( source)
- preg_replace: documentation ( source)
<?php
$matches = array();
$value = '#12
3ff;';
$value = preg_replace('/&#(\d+);?/me', "chr('\\1')", $value);
$value2 = preg_replace_callback('/&#(\d+);?/m', function($matches) {return chr($matches[1]);}, $value);
echo $value;