我在理解 python 2.7.2 中的 unicode 时遇到问题，所以我在空闲时尝试了一些测试。有两件事被标记为“不确定”。请告诉我为什么他们失败了。至于其他项目，请告诉我我的评论是否准确。
>>> s
'Don\x92t ' # s is a string
>>> u
u'Don\u2019t ' # u is a unicode object
>>> type(u) # confirm u is unicode
<type 'unicode'>
>>> type(s) # confirm s is string
<type 'str'>
>>> type(s) == 'str' # wrong way to test
False
>>> isinstance(s, str) # right way to test
True
>>> print s
Don’t # works because idle can handle strings
>>> print u
Don’t # works because idle can handle unicode
>>> open('9', 'w').write(s.encode('utf8')) #encode takes unicode, but s is a string,
# so this fails
Traceback (most recent call last):
File "<pyshell#28>", line 1, in <module>
open('9', 'w').write(s.encode('utf8'))
UnicodeDecodeError: 'ascii' codec can't decode byte 0x92 in position 3: ordinal not in range(128)
>>> open('9', 'w').write(s) # write can write strings
>>> open('9', 'w').write(u) # write can't write unicode
Traceback (most recent call last):
File "<pyshell#30>", line 1, in <module>
open('9', 'w').write(u)
UnicodeEncodeError: 'ascii' codec can't encode character u'\u2019' in position 3: ordinal not in range(128)
>>> open('9', 'w').write(u.encode('utf8')) # encode turns unicode to string, which write can handle
>>> open('9', 'w').write(s.decode('utf8')) # decode turns string to unicode, which write can't handle
Traceback (most recent call last):
File "<pyshell#32>", line 1, in <module>
open('9', 'w').write(s.decode('utf8'))
File "C:\program files\Python27\lib\encodings\utf_8.py", line 16, in decode
return codecs.utf_8_decode(input, errors, True)
UnicodeDecodeError: 'utf8' codec can't decode byte 0x92 in position 3: invalid start byte
>>> e = '{}, {}'.format(s, u) # fails becase ''.format is string, while u is unicode
Traceback (most recent call last):
File "<pyshell#33>", line 1, in <module>
e = '{}, {}'.format(s, u)
UnicodeEncodeError: 'ascii' codec can't encode character u'\u2019' in position 3: ordinal not in range(128)
>>> e = '{}, {}'.format(s, u.encode('utf8')) # works because u.encode is a string
>>> e = u'{}, {}'.format(s, u) # not sure
Traceback (most recent call last):
File "<pyshell#36>", line 1, in <module>
e = u'{}, {}'.format(s, u)
UnicodeDecodeError: 'ascii' codec can't decode byte 0x92 in position 3: ordinal not in range(128)
>>> e = u'{}, {}'.format(s.decode('utf8'), u) # not sure
Traceback (most recent call last):
File "<pyshell#55>", line 1, in <module>
e = u'{}, {}'.format(s.decode('utf8'), u)
File "C:\program files\Python27\lib\encodings\utf_8.py", line 16, in decode
return codecs.utf_8_decode(input, errors, True)
UnicodeDecodeError: 'utf8' codec can't decode byte 0x92 in position 3: invalid start byte
>>> e = '\n'.join([s, u]) # wants strings, but u is unicode
Traceback (most recent call last):
File "<pyshell#37>", line 1, in <module>
e = '\n'.join([s, u])
UnicodeDecodeError: 'ascii' codec can't decode byte 0x92 in position 3: ordinal not in range(128)
>>> e = '\n'.join([s, u.encode('utf8')]) # u.encode is now a string