Coding – Step 10.3 – Python from Zero – Conditional Menus

Step 10.3 – Python from Zero – Conditional Menus

Create a command-based menu with options: Add, View, and Exit

🧠 Why this lesson is important

In the first two lessons, we learned how to:

• Lesson 1 → Read input, use variables, and make decisions with if/else.
• Lesson 2 → Store multiple elements in a list and use loops to iterate over them.

Now, we’ll combine these skills to create an interactive program where the user selects actions from a menu and the program responds accordingly.

🎯 Goal

We will build a command-line To-Do List with these features:

• [A] Add a task
• [V] View all tasks
• [X] Exit the program

🏗️ Menu structure

1. Display the available options.
2. Read the user’s choice.
3. Execute the appropriate action using if/elif/else or match/case.
4. Repeat until the user chooses to exit.

📝 Base code

# todo_menu.py

tasks = []  # Task list

def show_menu():
    print("\n=== TO-DO MENU ===")
    print("[A] Add task")
    print("[V] View tasks")
    print("[X] Exit")

def add_task():
    text = input("Write the new task: ").strip()
    if text:
        tasks.append(text)
        print(f"✅ '{text}' added to the list!")
    else:
        print("⚠️  You didn't write anything, task not added.")

def view_tasks():
    if not tasks:
        print("📭 No tasks available.")
        return
    print("\n📋 Your tasks:")
    for i, t in enumerate(tasks, start=1):
        print(f"{i}. {t}")

def main():
    print("Welcome to your To-Do List!")
    while True:
        show_menu()
        choice = input("Choose an option: ").strip().lower()

        if choice == "a":
            add_task()
        elif choice == "v":
            view_tasks()
        elif choice == "x":
            print("Goodbye! 👋 See you next time.")
            break
        else:
            print("❌ Invalid command. Try again.")

if __name__ == "__main__":
    main()

🔍 How it works

• tasks = [] → creates an empty list to store tasks.
• show_menu() → displays the available options each time.
• add_task() → asks for a text input and adds it to the list if it’s not empty.
• view_tasks() → lists tasks or shows a message if there are none.
• main() → runs the loop, reads the choice, and calls the corresponding function.

💡 Alternative with match/case (Python ≥ 3.10)

while True:
    show_menu()
    choice = input("Choose an option: ").strip().lower()

    match choice:
        case "a":
            add_task()
        case "v":
            view_tasks()
        case "x":
            print("Goodbye! 👋 See you next time.")
            break
        case _:
            print("❌ Invalid command. Try again.")

🎨 Improving user experience

• Use emojis or symbols to make messages clearer.
• Add blank lines \n to make the output easier to read.
• Always normalize input with strip() and lower() to avoid errors.

🧩 Exercises

1. Task count: after displaying tasks, also show the total number (len(tasks)).
2. Multiple task addition: allow adding multiple tasks until the user types done.
3. Clear all tasks: add option [C] to clear the list after confirmation.
4. Numeric menu: allow numbers 1/2/0 as alternative menu options.

🚫 Common mistakes

• Not checking if the list is empty before printing it.
• Comparing input without strip() or lower() and failing to recognize commands.
• Forgetting break in the exit condition, causing the program to run indefinitely.

📌 Key takeaways

In this lesson, you learned to:

• Create an interactive menu in Python.
• Handle user input with multiple conditions.
• Organize your code into functions for clarity and maintainability.

In the next lesson, we will add functions to delete and mark tasks as complete, and to save data to a file.