> For the complete documentation index, see [llms.txt](https://jablack-programs.gitbook.io/python-notes/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://jablack-programs.gitbook.io/python-notes/python-spider/beautifulsoup/sou-suo-wen-dang-shu/guo-lv-qi/zheng-ze-biao-da-shi.md).

# 正则表达式

如果传入正则表达式作为参数,Beautiful Soup会通过正则表达式的`match()`来匹配内容.下面例子中找出所有以b开头的标签,这表示\<body>和\<b>标签都应该被找到:

```
import re
for tag in soup.find_all(re.compile("^b")):
    print(tag.name)
# body
# b
```

下面代码找出所有名字中包含”t”的标签:

```
for tag in soup.find_all(re.compile("t")):
    print(tag.name)
# html
# title
```