- preg_replace: documentation ( source)
<?php
$fmt = IntlDateFormatter::create('nl_NL', IntlDateFormatter::SHORT, IntlDateFormatter::NONE);
echo $fmt->format(1234567890), "\n";
$fmt->setPattern(preg_replace('~y+~', 'y', $fmt->getPattern()));
echo $fmt->format(1234567890), "\n";