To-Do List App

1) Project Overview

This project is a simple to-do list you use in the console (the black-and-white text screen). You can:

Add new tasks you want to do
See all your tasks with numbers
Mark a task as done
Delete a task you no longer need
Exit the program

It's like a small personal assistant that remembers your tasks while the program is running.

2) Learning Objectives

By building this project, you will practice:

Variables and data types (strings, booleans)
Lists (storing many tasks)
Dictionaries (keeping task text and done/not-done status together)
Loops (keep showing the menu until the user exits)
Functions (organizing code into small, reusable pieces)
Conditional statements (if/elif/else for choices)
User input and simple validation (handling mistakes nicely)
Basic logic and problem-solving

3) Step-by-Step Explanation

Follow these steps to build the app:

Plan the features
- We need a menu with options: Add, View, Mark Done, Delete, Exit.
- We need a place to store tasks.
Choose a data structure
- Use a list named tasks.
- Each task will be a dictionary like {"title": "Do homework", "done": False}.
- This way we keep both the text and whether it's done, together.
Make a function to show the menu
- Print the options 1–5 so the user can choose.
Make a function to display tasks
- If there are no tasks, tell the user.
- If there are tasks, print them with numbers starting at 1.
- Show a check mark for done tasks.
Make a function to add a task
- Ask the user for the task text.
- If they type something, add it to the list as not done yet.
- If they type nothing, remind them to enter something.
Make a function to mark a task as done
- If the list is empty, tell the user.
- Otherwise, show tasks and ask for a number.
- Convert the input to a number, check it's in range, then set done = True.
Make a function to delete a task
- Similar to marking as done, but remove the selected task from the list.
Build the main loop
- Keep showing the menu.
- Read the user's choice and call the matching function.
- If the user chooses Exit, say goodbye and stop the loop.
Test your app
- Try adding, viewing, marking done, deleting, and exiting.
- Try typing wrong inputs to see if the program handles them nicely.

4) Complete and Well-Commented Python Code

You can copy this into a file named todo_app.py and run it.

Try it Yourself »

# Simple To-Do List App (Console Version)

def show_menu():
    print("\n====== TO-DO LIST MENU ======")
    print("1) Add a task")
    print("2) View all tasks")
    print("3) Mark a task as done")
    print("4) Delete a task")
    print("5) Exit")
    print("=============================")

def print_tasks(tasks):
    """Show all tasks with numbers and done status."""
    if not tasks:
        print("\nNo tasks yet. Add your first task!")
        return

    print("\nYour tasks:")
    for i, task in enumerate(tasks, start=1):
        # If task["done"] is True, show a check mark ✓, otherwise a space
        status = "✓" if task["done"] else " "
        print(f"{i}. [{status}] {task['title']}")

def add_task(tasks):
    """Ask the user for a task and add it to the list."""
    title = input("\nType your new task: ").strip()
    if title == "":
        print("Oops! The task cannot be empty.")
        return
    tasks.append({"title": title, "done": False})
    print(f"Added: {title}")

def mark_task_done(tasks):
    """Mark a chosen task as done."""
    if not tasks:
        print("\nThere are no tasks to mark. Add one first.")
        return

    print_tasks(tasks)
    choice = input("\nEnter the task number to mark as done: ").strip()

    # Try to turn the input into a number
    try:
        index = int(choice) - 1  # user sees 1-based numbers, list uses 0-based
        if 0 <= index < len(tasks):
            if tasks[index]["done"]:
                print(f"Task already done: {tasks[index]['title']}")
            else:
                tasks[index]["done"] = True
                print(f"Marked as done: {tasks[index]['title']}")
        else:
            print("That number is not in the list.")
    except ValueError:
        print("Please enter a valid number.")

def delete_task(tasks):
    """Delete a chosen task from the list."""
    if not tasks:
        print("\nThere are no tasks to delete. Add one first.")
        return

    print_tasks(tasks)
    choice = input("\nEnter the task number to delete: ").strip()

    try:
        index = int(choice) - 1
        if 0 <= index < len(tasks):
            removed = tasks.pop(index)
            print(f"Deleted: {removed['title']}")
        else:
            print("That number is not in the list.")
    except ValueError:
        print("Please enter a valid number.")

def main():
    # Our list of tasks; each task is a dictionary with title and done status
    tasks = []

    print("Welcome to the To-Do List App!")

    while True:
        show_menu()
        choice = input("Choose an option (1-5): ").strip()

        if choice == "1":
            add_task(tasks)
        elif choice == "2":
            print_tasks(tasks)
        elif choice == "3":
            mark_task_done(tasks)
        elif choice == "4":
            delete_task(tasks)
        elif choice == "5":
            print("\nGoodbye! You did great today. Keep being organized!")
            break
        else:
            print("Please choose a number from 1 to 5.")

# This line runs the program when you run the file
if __name__ == "__main__":
    main()

5) Output Examples

Example session:

Welcome to the To-Do List App!

====== TO-DO LIST MENU ======
1) Add a task
2) View all tasks
3) Mark a task as done
4) Delete a task
5) Exit
=============================
Choose an option (1-5): 1

Type your new task: Do math homework
Added: Do math homework

====== TO-DO LIST MENU ======
1) Add a task
2) View all tasks
3) Mark a task as done
4) Delete a task
5) Exit
=============================
Choose an option (1-5): 1

Type your new task: Read 20 pages
Added: Read 20 pages

====== TO-DO LIST MENU ======
1) Add a task
2) View all tasks
3) Mark a task as done
4) Delete a task
5) Exit
=============================
Choose an option (1-5): 2

Your tasks:
1. [ ] Do math homework
2. [ ] Read 20 pages

====== TO-DO LIST MENU ======
1) Add a task
2) View all tasks
3) Mark a task as done
4) Delete a task
5) Exit
=============================
Choose an option (1-5): 3

Your tasks:
1. [ ] Do math homework
2. [ ] Read 20 pages

Enter the task number to mark as done: 2
Marked as done: Read 20 pages

====== TO-DO LIST MENU ======
1) Add a task
2) View all tasks
3) Mark a task as done
4) Delete a task
5) Exit
=============================
Choose an option (1-5): 2

Your tasks:
1. [ ] Do math homework
2. [✓] Read 20 pages

====== TO-DO LIST MENU ======
1) Add a task
2) View all tasks
3) Mark a task as done
4) Delete a task
5) Exit
=============================
Choose an option (1-5): 4

Your tasks:
1. [ ] Do math homework
2. [✓] Read 20 pages

Enter the task number to delete: 1
Deleted: Do math homework

====== TO-DO LIST MENU ======
1) Add a task
2) View all tasks
3) Mark a task as done
4) Delete a task
5) Exit
=============================
Choose an option (1-5): 5

Goodbye! You did great today. Keep being organized!

6) Small Exercise (Challenge)

Add an "Edit a task" option

Goal: Let the user change the text of an existing task.

Hints:

Add a new menu option: "6) Edit a task" (and adjust prompts).
Create a function edit_task(tasks) similar to delete_task.
Show the tasks, ask for a task number, and then ask for the new text.
Replace tasks[index]["title"] with the new text if it's not empty.
Test it with several tasks.

7) Summary

Great job! You built a complete console app using core Python skills: lists, dictionaries, loops, functions, and user input. These are the building blocks for bigger projects. Keep practicing, try the challenge, and remember: every small project makes you a stronger programmer. Keep going—you've got this!

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