- preg_replace: documentation ( source)
<?php
echo preg_replace('/\w+(__)\w+/i', '.', 'aluno_pobre__casado__novata');
$patterns = array ('/(19|20)(\d{2})-(\d{1,2})-(\d{1,2})/',
'/^\s*{(\w+)}\s*=/');
$replace = array ('\3/\4/\1\2', '$\1 =');
echo preg_replace($patterns, $replace, '{startDate} = 1999-5-27');
?>