example

# read()
# Read all at once

Open it in write mode
f = open('test_file.txt'.'w') 
f.write('Hello, \n xuxing! \n')
f.write('How do you do! ')
f.close()

f=open('test_file.txt'.'r+')
print(f.read())

# output
""" Hello, xuxing! How do you do! "" "
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File open mode

value describe
r Read mode (default)
w Write mode
x Exclusive write mode
a Attach mode
b Binary mode (used in combination with other modes)
+ Read/write mode
t Text mode (default)
  • Seek (N) moves the current position N units back
f=open('test_file.txt'.'r+')
# move down to 10 characters and write "TEST"
f.seek(10)
Where is the file currently located
f.seek(10)
print(f.tell())

f.write("TEST ")
f.seek(0)
print(f.read())

# output
10
Hello, 
 xTEST !
How do you do!
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  • Read one character at a time
with open('test_file.txt') as f:
    for char in f.read():
        print(char)
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  • Read one line at a time
# for loop
with open('test_file.txt') as f:
    for line in f.readlines():
        print(line)
        
# the while loop
with open('test_file.txt') as f:
    while True:
        line = f.readline()
        if not line:
            break
        print(line)
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  • Read multiple rows at a time
f=open('test_file.txt'.'r+')
lines = f.readlines()
f.close()

print(lines)

# -- -- -- -- -- -- -- -- -- -- -- --
import fileinput
for line in fileinput.input('test_file.txt') :print(line)
# output
['Hello, \n'.' xTEST ! \n'.'How do you do! ']
-----------
Hello, 

 xTEST !

How do you do!
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