- filter_var: documentation ( source)
- ini_set: documentation ( source)
- htmlspecialchars: documentation ( source)
<?php
ini_set('default_charset', 'UTF-8');
$string = '𝌆';
echo 'filter_var: ' . filter_var($string, FILTER_SANITIZE_FULL_SPECIAL_CHARS) . PHP_EOL;
echo 'htmlspecialchars: ' . htmlspecialchars($string, ENT_QUOTES);