Python_ Review 1

1: #r模式, a new file is not created when the file does not exist

f = open (' A.txt ', ' r ', encoding = ' utf-8 ')

2: Character encoding

What is character encoding?

Translate human characters into numbers that computers can recognize

What is a character encoding table?

Ascii

GBK

UTF-8

Unicode

Unicode-------->encode (' utf-8 ')-------------->bytes

Bytes------------>decode (' utf-8 ')--------------->unicode

Principle:

What format the character is compiled in and what format it will decode

Ps:

The characters in Python3 are divided into two types

x= ' Egon ' into Unicode

Y=x.encode (' Utf-8 ') saved into bytes

The strings in Python2 are also divided into two types

x = U ' Egon ' is the same as the string in Python3

Y= ' Alex ' is the same as the bytes type in Python3

#r模式的读, no new files are created when the file does not exist
f = open (' A.txt ', ' r ', encoding = ' utf-8 ')
print (F.read ())
f.close ()


#b模式即直接从硬盘中读取bytes
print (F.read (). Decode (' Utf-8 '))

#w文本模式的写, the file exists is emptied, does not exist and is created
f = open (' A.txt ', ' w ', encoding = ' utf-8 ')
f = open (' B.txt ', ' w ', encoding = ' utf-8 ')
print (f.writeable ()) #判断是否可写
print (f.readable ()) #判断是否可读

#a文本模式的追加
f = open (' B.txt ', ' a ', encoding = ' utf-8 ')
print (f.writeable ()) #写文件涉及到文件光标的移动
print (F.tell ())
print (F.readline ())
f.write (' 333\n ')
#r +,w+,a+, it can be written when read, can be read when written.

#rb模式即直接从硬盘中读取bytes
f = open (' a.txt ', ' RB ')
print (F.read (). Decode (' Utf-8 '))

#wb模式
f = open (' A.txt ', ' WB ')
f.write (' Hello '. Encode (' Utf-8 '))


# #b模式可以读取任何模式的文件
with open (' test.jpg ', ' RB ') as Read_f,\
open (' test1.jpg ', ' WB ') as Write_f:
For line in Read_f:
Write_f.write (line)

Python_ Review 1