📄 File Handling in Python | Lesson 14

📄 File Handling in Python

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Files help programs store and read data permanently, even after they close. Python makes it super easy to create, read, write, and manage files, so you can save user data, logs, or any important information. Let’s master file handling step-by-step! 📂

Basics of File Handling 🗂️

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Python works with files using built-in functions and methods, mainly through the open() function.

1. Opening a File 🔓

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Syntax:

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

Common modes:

2. Reading from a File 📖

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• Read whole content:

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()

3. Writing to a File ✍️

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• Write to a file (overwrites if exists):

file = open("example.txt", "w")
file.write("Hello, world!\n")
file.write("This is a new file.")
file.close()

• Append to a file (adds at end):

file = open("example.txt", "a")
file.write("\nAppending new line.")
file.close()

4. Using with Statement (Best Practice) 🏆

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with automatically closes the file even if errors occur:

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

Practice Questions with Solutions 🏆

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1. Write code to create a file notes.txt and write your favorite quote in it.
2. Write code to read and print all lines from notes.txt.
3. Append your name to notes.txt.
4. Read a file line by line and count the number of lines.

Step-by-Step Mini Project: Todo List Manager 🗒️

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Create a simple program to add and display tasks saved in a tasks.txt file.

def add_task(task):
    with open("tasks.txt", "a") as file:
        file.write(task + "\n")

def show_tasks():
    print("Your Tasks:")
    with open("tasks.txt", "r") as file:
        for line in file:
            print("-", line.strip())

# Usage
add_task("Complete Python course")
add_task("Go for a walk")
show_tasks()

Checklist for This Chapter ✅

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• Opened files in different modes (r, w, a)
• Read whole file or line by line
• Wrote and appended data to files
• Used with statement for safe file handling

You’re now ready to store and manage data on your computer through Python! Practice by creating notes, logs, and simple data storage apps! 🚀