4. File Basic Operation

File Operating Modes

Read the file

document content

Moonlight, suspected ground frost
I raise my eyes to the moon, looking down and think of home

1.read()

Read all the contents of the file

f = open('libai',encoding = 'utf-8')
print(f.read())

Moonlight, suspected ground frost
I raise my eyes to the moon, looking down and think of home

2.readline()

Only reads a single line

f = open('libai',encoding = 'utf-8')

print(f.readline())

Moonlight, suspected ground frost

3.readlines()

The content of the article with a newline character segmentation, and produces a list format (large volumes of data when not recommended)

f = open('libai',encoding = 'utf-8')

print(f.readlines())

[ ' Moonlight, suspected ground frost \ n- ' , ' give the first moon, down and think of home ' ]

4. seek and tell the cursor

f = open('libai',encoding='utf-8')
Data = reached, f.read ()      # default cursor at the starting position, read () after reading, the cursor to the end of the file 
data2 reached, f.read = ()     # contents read data2 is empty 
Print (Data)
 Print ( data2)
f.close ()           # close the file

file

abcdefg
hyjklmn
opqrst
vwxyz

Open = F ( ' libai ' , encoding = ' UTF-. 8 ' )
 # Tell gets the current cursor 
Print (f.tell ())     # 0

print(f.readline().strip())
print(f.readline().strip())
print(f.tell())
f.seek (0)      # Move the cursor to the file where the starting 
Print (f.readline (). Strip ())


result:
0
abcdefg
hyjklmn
18
abcdefg

5.flush Refresh

Simulation progress bar

import sys,time

for i in range(40):
    sys.stdout.write('#')
    sys.stdout.flush ()      # the flush cache memory pleasant force data is written to disk 
    time.sleep (0.1)

6.with statement

with code block after the implementation, the file is automatically turned off

with open('libai') as f:
    print(f.read())

7. binary reading "rb"

# RB reading the binary mode 
F = Open ( ' libai ' , ' RB ' )   # mainly used for network transmission 
Print (f.readline ())

b'\xe5\xba\x8a\xe5\x89\x8d\xe6\x98\x8e\xe6\x9c\x88\xe5\x85\x89\xef\xbc\x8c\xe7\x96\x91\xe6\x98\xaf\xe5\x9c\xb0\xe4\xb8\x8a\xe9\x9c\x9c\r\n'

8. binary writing "wb"

f = open('libai','wb')
f.write('中文'.encode())

Transcoding

method