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File Read and Write

File read and write is a common IO operation in programming.

Task​

There is a file called books.txt. Read the file and check if it contains the four great classical novels of China. If any novels are missing, add them to the file.

JavaScript implementation​

import fs from 'fs';

const data = fs.readFileSync('books.txt', 'utf8');
const books = data.split('\n');
const classics = ['The Story of the Stone', 'Journey to the West', 'Water Margin', 'Romance of the Three Kingdoms'];
const missingClassics = classics.filter(classic => !books.includes(classic));

if (missingClassics.length === 0) {
    console.log('The file already contains the four great classical novels of China.');
} else {
    const missingClassicsText = missingClassics.join('\n');
    fs.appendFileSync('books.txt', `\n${missingClassicsText}`, 'utf8');
    console.log(`The missing novels have been added to the file: ${missingClassicsText}`);
}

Python implementation​

# Read the contents of the file books.txt
with open('books.txt', 'r', encoding='utf-8') as file:
    books = file.read().splitlines()

# Check if the file contains the four great classical novels of China
classics = ['The Story of the Stone', 'Journey to the West', 'Water Margin', 'Romance of the Three Kingdoms']
missing_classics = [classic for classic in classics if classic not in books]

if len(missing_classics) == 0:
    print('The file already contains the four great classical novels of China.')
else:
    # Add the missing novels to the file
    with open('books.txt', 'a', encoding='utf-8') as file:
        file.write('\n' + '\n'.join(missing_classics))
    print(f'The missing novels have been added to the file: {", ".join(missing_classics)}')

Code Highlight​

  • In Python, use the open() function to open a file and use the with statement to ensure the file is properly closed.
  • In Python, use 'w', 'r', 'a' to specify the write, read, and append access modes of a file.

Difference Quick View​

FeatureJavaScriptPython
Read filefs.readFileSync(file, 'utf-8')open(file, 'r', encoding='utf-8').read()
Write to filefs.writeFileSync(file, data, 'utf-8')open(file, 'w', encoding='utf-8').write()
Append to filefs.appendFileSync(file, data, 'utf-8')open(file, 'a', encoding='utf-8').write()

Resources​