cat 连接字符串
<{$var|upper|cat:"test is a aa <br>"|cat:"hello word <br>"}>
$var 大写并且后面加上 "test is a aa hello word "字符串
date_format 格式化日期
<{$smarty.now|date_format:"%H-%y-%d "}> <br>
当前时间 年月日
regex_replace 正则替换
<{$var|regex_replace:"/\d/":"#"}> <br>
$var 中所有数字换成#
truncate截取
<{$var|truncate:30:"..."}> <br>
截取 $var 30个字符串 后面写...