• 错误1：变量加载到内存出现编码错误

文件内容a="中国"print a报错➜  ~ python a.py  File "a.py", line 1SyntaxError: Non-ASCII character '\xe4' in file b.py on line 1, but no encoding declared; see http://python.org/dev/peps/pep-0263/ for details

编译时读取变量a，因为包含中文，无法转化为str(ascii默认编码)存放到内存

磁盘字节串utf-8–>无法转为内存字节串str(ascii)

• 错误2：str直接encode报错

>>> sys.getdefaultencoding()'ascii'>>> a="中国">>> a.encode("gbk")Traceback (most recent call last):  File "
    
     ", line 1, in 
     
      UnicodeDecodeError: 'ascii' codec can't decode byte 0xe4 in position 0: ordinal not in range(128)>>> b=u"中国">>> b.encode("gbk")'\xd6\xd0\xb9\xfa'
     
    

变量a的类型是str(utf-8字节串)，会自动调用decode(默认编码ascii)，转为unicode，再调encode

自动decode时报错

• 错误3：编码相互转换报错

>>> "中国".decode("utf-8").encode("ascii")Traceback (most recent call last):  File "
    
     ", line 1, in 
     
      UnicodeEncodeError: 'ascii' codec can't encode characters in position 0-1: ordinal not in range(128)>>> "中国".decode("utf-8").encode("gbk")'\xd6\xd0\xb9\xfa'>>> "a".decode("utf-8").encode("ascii")'a'
     
    

ascii是utf-8的子集合，小集合转大集合没有问题

大集合转为小集合就报错不支持

• 错误4：unicode不能再decode

>>> a = "中国">>> b = a.decode("utf-8")>>> bu'\u4e2d\u56fd'>>> b.decode("utf-8")Traceback (most recent call last):  File "
    
     ", line 1, in 
     
        File "/usr/lib64/python2.7/encodings/utf_8.py", line 16, in decode    return codecs.utf_8_decode(input, errors, True)UnicodeEncodeError: 'ascii' codec can't encode characters in position 0-1: ordinal not in range(128)
     
    

• 总结

理解编码错误时，首先要判断str时以什么编码存放在内存中的，然后判断是否符合转换公式(str-(decode)->unicode-(encode)->str)。

判断方法，在python2中用len(str)或者bytes(str)可以判断，中文utf-8占3个字节，gbk占2个字节，ascii占一个字节。

印光大师十念法（胡小林主讲第1集）

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