Python 编码

1. 字符串的本质

字符 --> 字节 ：编码

字节--> 字符 ： 解码

2. 字符编码

字节和文本的编码和解码

字符编码

Ord 意思的order

chr 意思是 characte

ord("A")
Out[2]: 65
chr(127)
Out[3]: '\x7f'
chr(104)
Out[4]: 'h'
ord("宋")
Out[5]: 23435
# 只能传入一个整数 ord
ord("zeropython")
Traceback (most recent call last):
  File "/Users/songhao/anaconda3/lib/python3.6/site-packages/IPython/core/interactiveshell.py", line 2963, in run_code
    exec(code_obj, self.user_global_ns, self.user_ns)
  File "<ipython-input-6-ddb4f1055b9c>", line 1, in <module>
    ord("zeropython")
TypeError: ord() expected a character, but string of length 10 found
help(ord)
Help on built-in function ord in module builtins:
ord(c, /)
    Return the Unicode code point for a one-character string.
s = "zeropython"
# 将特定的字符串转换成特定的编码
s.encode("ascii")
Out[9]: b'zeropython'
s.encode("gbk")
Out[10]: b'zeropython'
s.encode("utf-8")
Out[11]: b'zeropython'
s.encode("unicode")
Traceback (most recent call last):
  File "/Users/songhao/anaconda3/lib/python3.6/site-packages/IPython/core/interactiveshell.py", line 2963, in run_code
    exec(code_obj, self.user_global_ns, self.user_ns)
  File "<ipython-input-12-ab39b0656cd1>", line 1, in <module>
    s.encode("unicode")
LookupError: unknown encoding: unicode
s2 = "从零开始学习Python zeropython"
s2.encode('ascii')
Traceback (most recent call last):
  File "/Users/songhao/anaconda3/lib/python3.6/site-packages/IPython/core/interactiveshell.py", line 2963, in run_code
    exec(code_obj, self.user_global_ns, self.user_ns)
  File "<ipython-input-14-91313a8298d3>", line 1, in <module>
    s2.encode('ascii')
UnicodeEncodeError: 'ascii' codec can't encode characters in position 0-5: ordinal not in range(128)
# ordinal not in range(128)
s2.encode('utf-8')
Out[15]: b'\xe4\xbb\x8e\xe9\x9b\xb6\xe5\xbc\x80\xe5\xa7\x8b\xe5\xad\xa6\xe4\xb9\xa0Python zeropython'
s2.encode('utf-16')
Out[16]: b'\xff\xfe\xceN\xf6\x96\x00_\xcbYf[`NP\x00y\x00t\x00h\x00o\x00n\x00 \x00z\x00e\x00r\x00o\x00p\x00y\x00t\x00h\x00o\x00n\x00'
s2.encode('utf-32')
Out[17]: b'\xff\xfe\x00\x00\xceN\x00\x00\xf6\x96\x00\x00\x00_\x00\x00\xcbY\x00\x00f[\x00\x00`N\x00\x00P\x00\x00\x00y\x00\x00\x00t\x00\x00\x00h\x00\x00\x00o\x00\x00\x00n\x00\x00\x00 \x00\x00\x00z\x00\x00\x00e\x00\x00\x00r\x00\x00\x00o\x00\x00\x00p\x00\x00\x00y\x00\x00\x00t\x00\x00\x00h\x00\x00\x00o\x00\x00\x00n\x00\x00\x00'
b1 = b'\xe4\xbb\x8e\xe9\x9b\xb6\xe5\xbc\x80\xe5\xa7\x8b\xe5\xad\xa6\xe4\xb9\xa0Python zeropython'
b1.decode('utf-8')

Out[19]: '从零开始学习Python zeropython'
b1.decode('utf-16')
Traceback (most recent call last):
  File "/Users/songhao/anaconda3/lib/python3.6/site-packages/IPython/core/interactiveshell.py", line 2963, in run_code
    exec(code_obj, self.user_global_ns, self.user_ns)
  File "<ipython-input-20-b6daf60ad93b>", line 1, in <module>
    b1.decode('utf-16')
UnicodeDecodeError: 'utf-16-le' codec can't decode byte 0x6e in position 34: truncated data
b1.decode('utf-32')
Traceback (most recent call last):
  File "/Users/songhao/anaconda3/lib/python3.6/site-packages/IPython/core/interactiveshell.py", line 2963, in run_code
    exec(code_obj, self.user_global_ns, self.user_ns)
  File "<ipython-input-21-761b37cda613>", line 1, in <module>
    b1.decode('utf-32')
UnicodeDecodeError: 'utf-32-le' codec can't decode bytes in position 0-3: code point not in range(0x110000)
s1
Traceback (most recent call last):
  File "/Users/songhao/anaconda3/lib/python3.6/site-packages/IPython/core/interactiveshell.py", line 2963, in run_code
    exec(code_obj, self.user_global_ns, self.user_ns)
  File "<ipython-input-22-d0257f733e5e>", line 1, in <module>
    s1
NameError: name 's1' is not defined
s1 = "从零开始学习"
s1.encode('utf-8')
Out[24]: b'\xe4\xbb\x8e\xe9\x9b\xb6\xe5\xbc\x80\xe5\xa7\x8b\xe5\xad\xa6\xe4\xb9\xa0'
b'\xe4\xbb\x8e\xe9\x9b\xb6\xe5\xbc\x80\xe5\xa7\x8b\xe5\xad\xa6\xe4\xb9\xa0'.decode('utf-8')
Out[25]: '从零开始学习'
b'\xe4\xbb\x8e\xe9\x9b\xb6\xe5\xbc\x80\xe5\xa7\x8b\xe5\xad\xa6\xe4\xb9\xa0'.decode('utf-16')
Out[26]: '믤\ue98e뚛볥\ue580讧귥\ue4a6ꂹ'
b'\xe4\xbb\x8e\xe9\x9b\xb6\xe5\xbc\x80\xe5\xa7\x8b\xe5\xad\xa6\xe4\xb9\xa0'.decode('utf-32')
Traceback (most recent call last):
  File "/Users/songhao/anaconda3/lib/python3.6/site-packages/IPython/core/interactiveshell.py", line 2963, in run_code
    exec(code_obj, self.user_global_ns, self.user_ns)
  File "<ipython-input-27-f8af0a75c110>", line 1, in <module>
    b'\xe4\xbb\x8e\xe9\x9b\xb6\xe5\xbc\x80\xe5\xa7\x8b\xe5\xad\xa6\xe4\xb9\xa0'.decode('utf-32')
UnicodeDecodeError: 'utf-32-le' codec can't decode bytes in position 0-3: code point not in range(0x110000)

获取系统默认编码

import sys
sys.getdefaultencoding()
Out[29]: 'utf-8'

类型转换

bytes 函数

bytes("vac",encoding="utf-8")
Out[31]: b'vac'
# bytes
bytes("你好")
Traceback (most recent call last):
  File "/Users/songhao/anaconda3/lib/python3.6/site-packages/IPython/core/interactiveshell.py", line 2963, in run_code
    exec(code_obj, self.user_global_ns, self.user_ns)
  File "<ipython-input-33-183eb72da6e1>", line 1, in <module>
    bytes("你好")
TypeError: string argument without an encoding
bytes("你好",'utf-8')
Out[34]: b'\xe4\xbd\xa0\xe5\xa5\xbd'
bytes(list(range(19)))
Out[35]: b'\x00\x01\x02\x03\x04\x05\x06\x07\x08\t\n\x0b\x0c\r\x0e\x0f\x10\x11\x12'
bytes(list(range(3)))
Out[36]: b'\x00\x01\x02'
bytes([2,3,4])
Out[37]: b'\x02\x03\x04'

函数 使用bytearry

# bytearry
bytearray("你好",'utf-8')
Out[39]: bytearray(b'\xe4\xbd\xa0\xe5\xa5\xbd')
s1 = bytearray("你好",'utf-8')
s1
Out[41]: bytearray(b'\xe4\xbd\xa0\xe5\xa5\xbd')
s1[0]
Out[42]: 228
s1[0] = 239
s1
Out[44]: bytearray(b'\xef\xbd\xa0\xe5\xa5\xbd')
s1.decode('utf-8')
Out[45]: '｠好'
s1.append("hell")
Traceback (most recent call last):
  File "/Users/songhao/anaconda3/lib/python3.6/site-packages/IPython/core/interactiveshell.py", line 2963, in run_code
    exec(code_obj, self.user_global_ns, self.user_ns)
  File "<ipython-input-46-b1556e6fe9cd>", line 1, in <module>
    s1.append("hell")
TypeError: 'str' object cannot be interpreted as an integer
s1.append(32)
s1.decode('utf-8')
Out[48]: '｠好 '
s1.append(65)
s1.decode('utf-8')
Out[50]: '｠好 A'
s1.decode('宋')
Traceback (most recent call last):
  File "/Users/songhao/anaconda3/lib/python3.6/site-packages/IPython/core/interactiveshell.py", line 2963, in run_code
    exec(code_obj, self.user_global_ns, self.user_ns)
  File "<ipython-input-51-389d78baf084>", line 1, in <module>
    s1.decode('宋')
LookupError: unknown encoding: 宋
s1.append("宋")
Traceback (most recent call last):
  File "/Users/songhao/anaconda3/lib/python3.6/site-packages/IPython/core/interactiveshell.py", line 2963, in run_code
    exec(code_obj, self.user_global_ns, self.user_ns)
  File "<ipython-input-52-66d780330da5>", line 1, in <module>
    s1.append("宋")
TypeError: 'str' object cannot be interpreted as an integer
"宋".encode('utf-8')
Out[53]: b'\xe5\xae\x8b'
"宋".encode('utf-8').decode('utf-8')
Out[54]: '宋'