py2默認的編碼是ascii, ascii只支持英文字符
In [2]: sys.getdefaultencoding()
Out[2]: 'ascii'
In [4]: a = '你好'
In [5]: a
Out[5]: '\xe4\xbd\xa0\xe5\xa5\xbd' # 輸出是十六進制的內存地址, 但其實還是bytes類型
In [6]: type(a) # 類型是str, 其實就是bytes
Out[6]: str
In [7]: b = 'hello'
In [8]: b
Out[8]: 'hello'
In [9]: type(b)
Out[9]: str
In [11]: a1 = a.decode('utf-8')
In [12]: a1
Out[12]: u'\u4f60\u597d' # 將bytes二進制按utf-8字符集解碼
In [13]: type(a1)
Out[13]: unicode # 變成了py2獨有的unicode類型
In [16]: sys.getsizeof(a) # bytes類型的你好
Out[16]: 43 # 字節大小
In [17]: sys.getsizeof(a1) # 解碼後的 你好
Out[17]: 54
In [19]: b1 = b.decode('utf-8')
In [20]: b1
Out[20]: u'hello'
In [22]: sys.getsizeof(b) # bytes類型佔的字節數少
Out[22]: 42
In [23]: sys.getsizeof(b1) # unicode佔字節數多
Out[23]: 60
py3默認的編碼是unicode, utf-8字符集
In [1]: import sys
In [2]: sys.getdefaultencoding()
Out[2]: 'utf-8'
In [3]: a = '你好'
In [4]: a
Out[4]: '你好'
In [5]: type(a) # py3的str就是str
Out[5]: str
In [6]: a1 = a.encode('utf-8')
In [7]: a1
Out[7]: b'\xe4\xbd\xa0\xe5\xa5\xbd' # 按默認編碼格式編碼後纔是bytes
In [8]: type(a1)
Out[8]: bytes