File Handling

Python File Handling Tutorial

Python provides built-in functions to read, write, and modify files easily. This tutorial covers file handling operations, including opening, reading, writing, and appending files, along with error handling techniques.

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1. Opening a File in Python

In Python, the open() function is used to open a file. The syntax is:

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

Example: Opening a File in Read Mode

file = open("sample.txt", "r")
print(file.read())  # Reads the content
file.close()

✅ Always close the file using close() to free up system resources.

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2. Writing to a File in Python

The 'w' mode overwrites the existing content, while 'a' mode appends to the file.

Example: Writing to a File

with open("sample.txt", "w") as file:
    file.write("Hello, Python!\n")
    file.write("This is a file handling tutorial.\n")

✅ Using with open() automatically closes the file after writing.

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Example: Appending to a File

with open("sample.txt", "a") as file:
    file.write("Appending new line.\n")

✅ Use 'a' mode to add content without deleting existing data.

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3. Reading from a File

Example: Read the Entire File

with open("sample.txt", "r") as file:
    content = file.read()
    print(content)

Example: Reading Line by Line

with open("sample.txt", "r") as file:
    for line in file:
        print(line.strip())  # strip() removes extra spaces and newlines

Example: Reading Specific Number of Characters

with open("sample.txt", "r") as file:
    print(file.read(10))  # Reads first 10 characters

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4. File Handling with Exception Handling

To prevent errors, wrap file operations in a try-except block.

try:
    with open("non_existent.txt", "r") as file:
        print(file.read())
except FileNotFoundError:
    print("Error: File not found!")

✅ Best practice: Always handle file-related errors gracefully.

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5. Working with Binary Files

Binary mode ('b') is used for images, PDFs, and audio/video files.

Example: Copy an Image File

with open("image.jpg", "rb") as source_file:
    with open("copy.jpg", "wb") as destination_file:
        destination_file.write(source_file.read())

✅ Use 'rb' and 'wb' for handling non-text files.

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6. Deleting a File

Use the os module to delete a file.

import os

if os.path.exists("sample.txt"):
    os.remove("sample.txt")
    print("File deleted successfully.")
else:
    print("File does not exist.")

✅ Always check if the file exists before deleting it.

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Conclusion

Python's file handling features allow reading, writing, appending, and managing files efficiently. Always use with open() for automatic resource management and handle errors using try-except blocks.

For hands-on learning, try creating a file-based project, such as a simple text editor or a log manager!

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