April 2023
Intermediate to advanced
769 pages
25h 16m
Chinese
Content preview from 流畅的Python（第2版）
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98
｜
第
4
章
字节序只对一个字（
word
）占多个字节的编码（例如
UTF-16
和
UTF-32
）有影响。
UTF-8
的一大优势是，不管设备使用哪种字节序，生成的字节序列始终一致，因此不需要
BOM
。
尽管如此，某些
W
indows
应用程序（比如
Notepad
）依然会在
UTF-8
编码的文件中添加
BOM
。而且
，
Excel
会根据有没有
BOM
来确定文件是不是
UTF-8
编码，不然它就假设内
容使用
W
indows
代码页（
code page
）编码。带有
BOM
的
UTF-8
编码，在
Python
注册的
编码解码器中叫作
UTF-8-SIG
。
UTF-8-SIG
编码的
U+FEFF
字符是一个三字节序列
：
b'\
xef\xbb\xbf'
。因此，如果文件以这三个字节开头，可能就是带有
BOM
的
UTF-8
文件。
Caleb
建议使用
UTF-8-SIG
本书技术审校
Caleb
Hattingh
建议始终使用
UTF-8-SIG
编码解码器读取
UTF-8
文件
。这样做没有任何问题，因为不管文件带不带
BOM
，
UTF-8-SIG
都能正确读取，而且不返回
BOM
本身
。不过，我在书中建议使用
UTF-8
，
方便互操作。举个例子，在
Unix
系统中，如果
Python
脚本以注释
#!/usr/
bin/env python3
开头，则可以用作可执行文件。为此，文件的前两个字节
必须是
b'#!'
，而有了
BOM
，这个约定就被打破了。如果你需要导出带有
BOM
的数据
，供其他应用使用，应使用
UTF-8-SIG
。但是，请记住
Python
编码解码器文档中的一句话：“不鼓励也不建议为
UTF-8 ...
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.