Python File Handling

Learn the basics of working with files in Python - Start from zero!

📁 Welcome to File Handling!

File handling lets your Python programs save data, read information, and work with files on your computer. Think of it like teaching your program to read books and write notes! 


# This is how easy it is to work with files!
with open('my_file.txt', 'w') as file:
    file.write('Hello from Python!')

print("File created! 🎉")
Simple
To Learn
5
File Modes
Safe
Methods

What is File Handling?

File handling is like giving your Python program the ability to:

  • 📖 Read information from files (like reading a book)
  • ✍️ Write information to files (like writing in a notebook)
  • ➕ Add new information to existing files
  • 🗑️ Delete files when you don't need them

Understanding File Modes

📖

Read Mode ('r')

Opens file for reading only

Default mode File must exist
✏️

Write Mode ('w')

Creates new file or replaces existing

Creates new Overwrites existing
➕

Append Mode ('a')

Adds content to end of existing file

Keeps old content Adds to end
🔄

Read-Write Mode ('r+')

Both read and write in same file

Advanced Flexible

Your First File Operation

The Basic Way (Not Recommended) 

# Old way - you have to remember to close the file
file = open('example.txt', 'w')
file.write('Hello World!')
file.close()  # Don't forget this!

print("File created the old way")
The Modern Way (Recommended) ✅ 

# Modern way - file closes automatically!
with open('example.txt', 'w') as file:
    file.write('Hello World!')
# File is automatically closed here

print("File created the modern way!")

🌟 Why use 'with'?

  • Automatically closes the file when done
  • Works even if there's an error
  • Cleaner and safer code
  • This is how professionals do it!

Let's Try Different Modes

Creating a File (Write Mode) 

# Create a new file
with open('my_story.txt', 'w') as file:
    file.write('Once upon a time...')

print("✅ Story file created!")
Reading a File (Read Mode) 

# Read the file we just created
try:
    with open('my_story.txt', 'r') as file:
        content = file.read()
        print(f"Story content: {content}")
except FileNotFoundError:
    print("❌ File not found!")
Adding to a File (Append Mode) 

# Add more to our story
with open('my_story.txt', 'a') as file:
    file.write(' And they lived happily ever after!')

print("✅ Story completed!")

# Read the complete story
with open('my_story.txt', 'r') as file:
    complete_story = file.read()
    print(f"Complete story: {complete_story}")

Detailed File Modes

Basic Syntax: File Modes

Common file modes

  • 'r' Read mode (default) - opens file for reading
  • 'w' Write mode - creates new file or truncates existing
  • 'a' Append mode - opens file for writing at end of file
  • 'r+' Read-write mode - opens file for both reading and writing
  • 'w+' Write-read mode - creates new file or truncates existing for reading and writing
  • 'a+' Append-read mode - opens file for reading and writing at end of file

Binary modes (add 'b' to any mode)

  • 'rb' Read binary mode
  • 'wb' Write binary mode
  • 'ab' Append binary mode

Text mode with encoding

open('file.txt', 'r', encoding='utf-8') # Specify encoding

Handling Errors Like a Pro

Safe File Operations 

# Safe way to open files
def safe_read_file(filename):
    try:
        with open(filename, 'r') as file:
            content = file.read()
            print(f"✅ Successfully read {filename}")
            return content
    except FileNotFoundError:
        print(f"❌ File '{filename}' not found!")
    except PermissionError:
        print(f"❌ No permission to read '{filename}'!")
    except Exception as error:
        print(f"❌ Something went wrong: {error}")
    return None

# Test it
safe_read_file('my_story.txt')
safe_read_file('missing_file.txt')

Getting File Information

Check File Properties 

import os
from datetime import datetime

# Create a test file
with open('info_test.txt', 'w') as file:
    file.write('This file is for testing file information!')

# Get file information
filename = 'info_test.txt'

if os.path.exists(filename):
    # File size
    size = os.path.getsize(filename)
    print(f"📏 File size: {size} bytes")
    
    # Last modified time
    mod_time = os.path.getmtime(filename)
    readable_time = datetime.fromtimestamp(mod_time)
    print(f"🕒 Last modified: {readable_time}")
    
    # File path info
    print(f"📁 Full path: {os.path.abspath(filename)}")
    print(f"📄 Just filename: {os.path.basename(filename)}")
    
    # Check permissions
    print(f"👀 Can read: {os.access(filename, os.R_OK)}")
    print(f"✏️ Can write: {os.access(filename, os.W_OK)}")
else:
    print(f"❌ File '{filename}' doesn't exist!")

Working with Binary Files

Binary File Example 

# Working with binary files (like images, videos, etc.)
binary_data = b"This is binary data"

# Write binary file
with open('data.bin', 'wb') as file:
    file.write(binary_data)

print("✅ Binary file created!")

# Read binary file
with open('data.bin', 'rb') as file:
    read_data = file.read()
    print(f"📊 Binary data: {read_data}")
    print(f"📊 As text: {read_data.decode()}")

Modern File Handling with pathlib

Using pathlib (Python 3.4+) 

from pathlib import Path

# Create a Path object
file_path = Path('modern_example.txt')

# Write to file
file_path.write_text('Hello from modern Python!')

# Read from file
content = file_path.read_text()
print(f"📄 Content: {content}")

# Check if file exists
if file_path.exists():
    print(f"✅ File exists!")
    print(f"📏 Size: {file_path.stat().st_size} bytes")
    print(f"📁 Parent directory: {file_path.parent}")
    print(f"🏷️ File name: {file_path.name}")
    print(f"🔤 File extension: {file_path.suffix}")

Best Practices for Beginners

✅ Always Use 'with'

Use with open() instead of just open()

🛡️ Handle Errors

Use try/except to handle file errors gracefully

🎯 Choose Right Mode

'r' for reading, 'w' for writing, 'a' for appending , 'b' for binary mode

🌍 Specify Encoding

Use encoding='utf-8' for text files

🎯 Practice Time!

Create a Simple File Manager 

# Simple file manager functions
import os

def create_file(filename, content):
    """Create a new file with content"""
    try:
        with open(filename, 'w') as file:
            file.write(content)
        print(f"✅ Created '{filename}'")
        return True
    except Exception as e:
        print(f"❌ Error creating '{filename}': {e}")
        return False

def read_file(filename):
    """Read and display file content"""
    try:
        with open(filename, 'r') as file:
            content = file.read()
        print(f"📄 Content of '{filename}':")
        print(content)
        return content
    except FileNotFoundError:
        print(f"❌ File '{filename}' not found!")
        return None

def check_file(filename):
    """Check if file exists and show info"""
    if os.path.exists(filename):
        size = os.path.getsize(filename)
        print(f"✅ '{filename}' exists - Size: {size} bytes")
        return True
    else:
        print(f"❌ '{filename}' doesn't exist")
        return False

# Test our file manager
create_file('test.txt', 'Hello, this is a test file!')
check_file('test.txt')
read_file('test.txt')

🧠 Test Your Knowledge

Which is the recommended way to open a file in Python?

Which file mode creates a new file or overwrites an existing one?

What happens when you try to read a file that doesn't exist?