Differences between Python, read (), readline (), readlines ()

Note the difference between read (), readline (), and readlines ()

Premise

For example, suppose you have the following text files in the tests directory:

articles.txt

Marble,Sleepy
White,I'm hungry
Black,Somehow warm
Marble,Poe Poe Poe

(1) read () * There is a character limit

The read method gets the entire opened file as a string. \ n is included. Entering a number in the argument limits the number of characters.

with open('tests/articles.txt',encoding='utf-8') as f:
    test = f.read(10)
    print(test)

Then

Marble,Sleepy
Shi

Will be.

(2) read () * No character limit

If nothing is entered in the argument, everything will be acquired.

with open('tests/articles.txt',encoding='utf-8') as f:
    test = f.read()
    print(test)

Then

Marble,Sleepy
White,I'm hungry
Black,Somehow warm
Marble,Poe Poe Poe

Will be.

（３）readline If you execute it as it is, only one line of the file will be read.

with open('tests/articles.txt',encoding='utf-8')as f:
    test= f.readline()
    print(test)

Then

Marble,Sleepy

Will be.

（４）readlines You can get the entire file as a line-by-line list.

with open('tests/articles.txt',encoding='utf-8')as f:
    test= f.readlines()
    print(test)

Then

['Marble,Sleepy\n', 'White,I'm hungry\n', 'Black,Somehow warm\n', 'Marble,Poe Poe Poe\n']

Will be.

(5) Summary

Set the articles text file in the tests directory and run test.py The summary is as follows.

┬test.py
└tests
  └articles.txt

articles.txt

Marble,Sleepy
White,I'm hungry
Black,Somehow warm
Marble,Poe Poe Poe

.python:test.py

with open('tests/articles.txt',encoding='utf-8') as f:
    test = f.read(10)
    print('\n'+'\n'+test)

print('\n--------------------------\n')


with open('tests/articles.txt',encoding='utf-8') as f:
    test = f.read()
    print(test)

print('\n--------------------------\n')

with open('tests/articles.txt',encoding='utf-8') as f:
    test= f.readline()
    print(test)

print('\n--------------------------\n')

with open('tests/articles.txt',encoding='utf-8') as f:
    test= f.readlines()
    print(test)
print('\n'+'\n')

Marble,Sleepy
Shi

--------------------------

Marble,Sleepy
White,I'm hungry
Black,Somehow warm
Marble,Poe Poe Poe


--------------------------

Marble,Sleepy


--------------------------

['Marble,Sleepy\n', 'White,I'm hungry\n', 'Black,Somehow warm\n', 'Marble,Poe Poe Poe\n']