File I/O in Python

1. Introduction

File Input/Output (I/O) in Python is a fundamental concept that allows you to read from and write to files on your system. This lesson covers the essential functions and methods for handling file I/O in Python.

2. Opening Files

In Python, you can open a file using the built-in open() function. The basic syntax is:

file = open('filename.txt', 'mode')

Modes:

• 'r' - Read (default mode)
• 'w' - Write (overwrites existing file)
• 'a' - Append (adds to the end of the file)
• 'b' - Binary mode (for non-text files)
• 'x' - Exclusive creation (fails if the file exists)

3. Reading Files

To read the contents of a file, you can use the read(), readline(), or readlines() methods.

file = open('filename.txt', 'r')
content = file.read()
file.close()

You can also use a context manager to ensure the file is closed automatically:

with open('filename.txt', 'r') as file:
    content = file.read()

4. Writing Files

To write data to a file, you can use the write() or writelines() methods:

with open('filename.txt', 'w') as file:
    file.write("Hello, World!")

5. Closing Files

It is crucial to close files after their operations are complete to free up system resources. This can be done using the close() method, but using a context manager (as shown above) is preferred.

6. Best Practices

• Always use a context manager when working with files.
• Handle exceptions using try-except blocks.
• Use relative paths when possible to enhance portability.
• Ensure to use the correct file modes to avoid data loss.

7. FAQ