> For the complete documentation index, see [llms.txt](https://stb11816.gitbook.io/python_note/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://stb11816.gitbook.io/python_note/crawler/kong-zhi-zi-7b2628-control-character.md).

# 控制字符(control character)

看不到但確實存在的幽靈字符，可使用re進行替換，比replace來的方便些

## re

```python
# python3
import re
text = '你\u202a好阿\u202e陌生人'  # 參雜控制字符
print(text, [text], len(text))  # 長度為8 (6+2)

# 將特定範圍的符號替換為空字串
str_input = re.sub(r'[\u200b-\u200f \u2029-\u202e \u2061-\u2064 \u206a-\u206f]', "", text)

print(str_input, [str_input], len(str_input))  # 長度為2
```

## 檢查控制符號內容

在python3可使用內建函數來查看字符編碼與內容

ord(str)：回傳在unicode中的對應編號

chr(int)：回傳編號所對應的unicode

目前遇到的幽靈字符範圍如下：

| 字符                 | 編碼         |
| ------------------ | ---------- |
| "\u200b"\~"\u200f" | 8203\~8207 |
| "\u2029"\~"\u202e" | 8233\~8239 |
| "\u2061"\~"\u2064" | 8289\~8292 |
| "\u206a"\~"\u206f" | 8298\~8303 |

```python
# python3
# 輸出編碼與字符
for i in range(8000, 9000):
    print(chr(i), ord(chr(i))) # 字符, 編碼
```

奇怪的空格

| 字符       | 編碼           |
| -------- | ------------ |
| "\u3000" | 12288 (全形空格) |
| "\u202f" | 8239         |
| "\u205f" | 8287         |
| "\xa0"   | 160          |

替換空格

```python
# python3
import re
text = '你\u202a\u202a好阿\u202e陌生\u202f人'  # 參雜控制字符
print(text, [text], len(text))  # 長度為8 (6+2)
str_input = re.sub(r'[\u202f\u205f\u3000]', " ", text)
print(str_input, [str_input], len(str_input))
```

參考資料：\
<https://www.itread01.com/article/1486433903.html>\
<https://dotblogs.com.tw/law1009/2013/07/13/109833>\
<https://www.programcreek.com/python/example/144/re.VERBOSE>


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