字符串过滤器
最后更新于：2022-04-02 02:31:54
[TOC]
## string.rot13
字母后移13位
```
$fp = fopen("php://output",'wb');
stream_filter_append($fp,"string.rot13");
fwrite($fp,"123abc"); // 123nop
```
## string.toupper / string.tolower
```
$fp = fopen("php://output",'wb');
stream_filter_append($fp,"string.toupper");
fwrite($fp,"123abc"); // 123ABC
```
## string.strip_tags
```
$fp = fopen('php://output', 'wb');
stream_filter_append($fp, 'string.strip_tags');
fwrite($fp, "bolded text enlarged to a
';