PHP替换中文字符

mb_regex_encoding('utf-8');
$htmlNavSubmenu2 = str_replace('<li id="w-menu-food-334"><a href="food.php?cid=334">','',$htmlNavSubmenu);
$htmlNavSubmenu3 = mb_ereg_replace('欢迎页面</a></li>','',$htmlNavSubmenu2);
echo $htmlNavSubmenu3;