File Handling

File handling involves reading from and writing to files, enabling programs to interact with external data storage. Python provides built-in functions and methods to manage files efficiently, with support for text, binary, and various file formats.

Mode Description
'r' Read (default). Error if file doesn't exist.
'w' Write. Creates file or overwrites existing.
'a' Append. Adds to end; creates if not exist.
'x' Exclusive creation. Error if file exists.
'r+' Read and write. Error if file doesn't exist.
'w+' Read and write. Creates/overwrites file.
'rb', 'wb', etc. Binary mode (e.g., for images, videos).

File Operations

Opening File


file = open("example.txt", "r")
file.close()

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

# File is automatically closed after the block

Reading File

a) Read Entire File
with open('example.txt', 'r') as file:
    content = file.read()
    print(content)
b) Read Line by Line
with open('example.txt', 'r') as file:
    for line in file:
        print(line.strip())
c) Read Specific Amount
with open('example.txt', 'r') as file:
    chunk = file.read(10)
    print(chunk)

Writing to File

a) Write New Content
with open('example.txt', 'w') as file:
    file.write("Hello, World!\n")
b) Append
with open('example.txt', 'a') as file:
    file.write("\nNew line appended")

Binary File Handling

For non-text files.

with open('image.jpg', 'rb') as file:
    binary_data = file.read()

with open('image_copy.jpg', 'wb') as file:
    file.write(binary_data)

CSV File Handling

Working with CSV files.

import csv
with open('data.csv', 'w', newline='') as file:
    writer = csv.writer(file)
    writer.writerow(['Name', 'Age'])

Key Features

  • Multiple file modes
  • Automatic closing
  • Text and binary support
  • Error handling

Best Practices

  • Use `with` statement
  • Handle exceptions
  • Specify encoding
  • Check file existence