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File I/O

File handling involves performing various operations on files, such as reading, writing, and modifying their contents. Python provides built-in functions and methods to work with files efficiently.

Opening and Closing Files​

# Opening a file in read mode
file = open("example.txt", "r")

# Opening a file in write mode
file = open("output.txt", "w")

# Opening a file in append mode
file = open("data.txt", "a")

# Closing a file
file.close()

Reading Data from Files​

# Reading the entire file content
with open("example.txt", "r") as file:
    content = file.read()

# Reading line by line
with open("example.txt", "r") as file:
    for line in file:
        print(line.strip())

Writing Data to Files​

# Writing to a file
with open("output.txt", "w") as file:
    file.write("Hello, World!")

# Writing multiple lines
lines = ["Line 1", "Line 2", "Line 3"]
with open("output.txt", "w") as file:
    file.writelines(lines)

Appending Data to Files​

# Appending to a file
with open("data.txt", "a") as file:
    file.write("New data")

Working with Text and Binary Modes​

# Reading a binary file
with open("image.jpg", "rb") as file:
    binary_data = file.read()

# Writing binary data to a file
with open("new_image.jpg", "wb") as file:
    file.write(binary_data)

Using with Statements for File Handling​

# Using 'with' statement for automatic file closing
with open("example.txt", "r") as file:
    content = file.read()

Handling Exceptions with Files​

try:
    with open("missing_file.txt", "r") as file:
        content = file.read()
except FileNotFoundError:
    print("File not found.")

File Iteration​

with open("example.txt", "r") as file:
    lines = file.readlines()
for line in lines:
    print(line.strip())

File Seek and Tell​

with open("example.txt", "r") as file:
    content = file.read(10)  # Read the first 10 characters
    position = file.tell()   # Get the current file pointer position
    file.seek(0)             # Move the file pointer to the beginning

Working with Directories​

import os

# List all files and directories in a directory
contents = os.listdir("/path/to/directory")

# Create a new directory
os.mkdir("/path/to/new_directory")

# Remove a file or directory
os.remove("file.txt")
os.rmdir("empty_directory")

Practical Examples​

  • CSV File Handling: Reading and writing data in CSV files.
  • JSON File Handling: Reading and writing data in JSON files.
  • Log File Handling: Writing logs to a file for debugging.
  • Image Manipulation: Reading, editing, and saving image files.