File Handling in Python

Introduction

File handling is an essential part of any programming language. Python provides built-in functions and methods to handle files. Whether you want to read, write, or manipulate files, Python makes it easy and intuitive. This guide will cover basic file operations and the os module for advanced file handling.

Opening a File

In Python, you can open a file using the open() function. The open() function requires a file path and a mode (optional). The mode specifies what you want to do with the file: read, write, append, etc.

# Open a file for reading
file = open('example.txt', 'r')

# Open a file for writing
file = open('example.txt', 'w')

# Open a file for appending
file = open('example.txt', 'a')

Reading from a File

To read from a file, you can use methods like read(), readline(), or readlines(). Here’s how:

# Read the entire file
file = open('example.txt', 'r')
content = file.read()
print(content)
file.close()

# Read line by line
file = open('example.txt', 'r')
for line in file:
    print(line, end='')
file.close()

Writing to a File

Writing to a file is straightforward using the write() method. Make sure to open the file in write ('w') or append ('a') mode.

# Write to a file
file = open('example.txt', 'w')
file.write('Hello, World!')
file.close()

# Append to a file
file = open('example.txt', 'a')
file.write('\nAppended text.')
file.close()

Closing a File

It’s important to close a file after you’ve finished working with it to free up system resources. Use the close() method.

# Close a file
file = open('example.txt', 'r')
# Perform file operations
file.close()

Using with Statement

Python provides a more efficient way to handle files using the with statement. This ensures that the file is properly closed after its suite finishes, even if an exception is raised.

# Using with statement
with open('example.txt', 'r') as file:
    content = file.read()
    print(content)

Using the os Module

The os module in Python provides a way to interact with the operating system. It includes functions to handle file and directory operations such as checking for the existence of a file, deleting a file, and creating directories.

Checking if a File Exists

Before performing operations on a file, it's often a good idea to check if the file exists. You can use the os.path.exists() function for this purpose.

import os

if os.path.exists('example.txt'):
    print('The file exists.')
else:
    print('The file does not exist.')

Deleting a File

To delete a file, you can use the os.remove() function.

import os

if os.path.exists('example.txt'):
    os.remove('example.txt')
    print('File deleted.')
else:
    print('The file does not exist.')

Creating a Directory

You can create a new directory using the os.makedirs() function.

import os

os.makedirs('new_directory')
print('Directory created.')

Listing Files in a Directory

To list all files and directories in a specific directory, you can use the os.listdir() function.

import os

files = os.listdir('.')
print('Files and directories in the current directory:')
for file in files:
    print(file)

Getting the Current Working Directory

You can get the current working directory using os.getcwd().

import os

cwd = os.getcwd()
print('Current working directory:', cwd)

Changing the Current Working Directory

You can change the current working directory using os.chdir().

import os

os.chdir('new_directory')
print('Changed working directory to new_directory')

Renaming a File

You can rename a file using os.rename().

import os

if os.path.exists('example.txt'):
    os.rename('example.txt', 'new_example.txt')
    print('File renamed.')
else:
    print('The file does not exist.')

Summary

File handling in Python is simple yet powerful. By understanding how to open, read, write, and close files, you can efficiently manage your data within your programs. The os module further enhances these capabilities by allowing you to interact with the file system at a deeper level. Remember to use the with statement for cleaner and more readable code.