python字符串编码解码的使用

>>> ord('梯')
26799
>>> chr(26799)
'梯'

>>> b=b'abc' # 返回每个字符的原始字节的整数
>>> s='abc'
>>> type(b),type(s)
(<class 'bytes'>, <class 'str'>)
>>> b,s
(b'abc', 'abc')
>>> b[0],s[0]
(97, 'a')
>>> b[1:],s[1:]
(b'bc', 'bc')
>>> list(b),list(s)
([97, 98, 99], ['a', 'b', 'c'])
# bytes 和 str 不可修改
>>> b[0]='d'
Traceback (most recent call last):
  File "<pyshell#32>", line 1, in <module>
    b[0]='d'
TypeError: 'bytes' object does not support item assignment
>>> s[0]='d'
Traceback (most recent call last):
  File "<pyshell#33>", line 1, in <module>
    s[0]='d'
TypeError: 'str' object does not support item assignment
>>> c=b'''
abc
def
'''
>>> c
b'\nabc\ndef\n'

>>> import sys
# 查看系统
>>> sys.platform
'win32'
# 查看系统默认编码
>>> sys.getdefaultencoding()
'utf-8'
>>> s='梯'
# encode 和 bytes 编码，字符串转原始字节
>>> s.encode()# encoding 默认为 utf-8
b'\xe6\xa2\xaf'
>>> s.encode(encoding='utf-8')
b'\xe6\xa2\xaf'
>>> s.encode(encoding='gbk')
b'\xcc\xdd'
>>> bytes(s,encoding='gbk')
b'\xcc\xdd'
>>> bytes(s,encoding='utf-8')
b'\xe6\xa2\xaf'
# decode 和 str 解码，原始字节转字符串
>>> b=b'\xe6\xa2\xaf'
>>> b.decode()
'梯'
>>> str(b,encoding='utf-8')
'梯'
# str() 没有 encoding ，则 进行打印
>>> str(b)
"b'\\xe6\\xa2\\xaf'"
# bytes() 没有 encoding ，则 报错
>>> bytes(s)
Traceback (most recent call last):
  File "<pyshell#62>", line 1, in <module>
    bytes(s)
TypeError: string argument without an encoding