Build a Python script to manage to-do lists

Here’s a comprehensive Python script to manage to-do lists with essential features like adding, viewing, updating, and deleting tasks. It uses simple file storage (JSON) to persist data between runs.

python
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import json
import os

TODO_FILE = "todo_list.json"

def load_tasks():
    if not os.path.exists(TODO_FILE):
        return []
    with open(TODO_FILE, "r") as f:
        return json.load(f)

def save_tasks(tasks):
    with open(TODO_FILE, "w") as f:
        json.dump(tasks, f, indent=4)

def show_tasks(tasks):
    if not tasks:
        print("No tasks in your to-do list.")
        return
    print("nYour To-Do List:")
    for idx, task in enumerate(tasks, 1):
        status = "✓" if task["completed"] else "✗"
        print(f"{idx}. [{status}] {task['task']}")

def add_task(tasks):
    task_desc = input("Enter the task description: ").strip()
    if task_desc:
        tasks.append({"task": task_desc, "completed": False})
        print("Task added.")
    else:
        print("Task description cannot be empty.")

def mark_task_completed(tasks):
    show_tasks(tasks)
    try:
        task_num = int(input("Enter the task number to mark as completed: "))
        if 1 <= task_num <= len(tasks):
            tasks[task_num - 1]["completed"] = True
            print("Task marked as completed.")
        else:
            print("Invalid task number.")
    except ValueError:
        print("Please enter a valid number.")

def delete_task(tasks):
    show_tasks(tasks)
    try:
        task_num = int(input("Enter the task number to delete: "))
        if 1 <= task_num <= len(tasks):
            deleted = tasks.pop(task_num - 1)
            print(f"Deleted task: {deleted['task']}")
        else:
            print("Invalid task number.")
    except ValueError:
        print("Please enter a valid number.")

def main():
    tasks = load_tasks()
    while True:
        print("nOptions:")
        print("1. View tasks")
        print("2. Add task")
        print("3. Mark task as completed")
        print("4. Delete task")
        print("5. Exit")
        choice = input("Choose an option (1-5): ").strip()

        if choice == '1':
            show_tasks(tasks)
        elif choice == '2':
            add_task(tasks)
            save_tasks(tasks)
        elif choice == '3':
            mark_task_completed(tasks)
            save_tasks(tasks)
        elif choice == '4':
            delete_task(tasks)
            save_tasks(tasks)
        elif choice == '5':
            print("Goodbye!")
            break
        else:
            print("Invalid option, please try again.")

if __name__ == "__main__":
    main()

This script allows you to:

• Add new tasks

• View all tasks with completion status

• Mark tasks as completed

• Delete tasks

• Save tasks persistently in a JSON file

Run this in a terminal, and it will manage your to-do list interactively.