Introduction : To-Do List App with Python

				
					import os

class ToDoList:
    def __init__(self, file_name="tasks.txt"):
        self.tasks = []
        self.file_name = file_name
        self.load_tasks()

    def load_tasks(self):
        """Load tasks from a file."""
        if os.path.exists(self.file_name):
            with open(self.file_name, "r") as file:
                for line in file:
                    task, priority = line.strip().split("|")
                    self.tasks.append({"task": task, "priority": int(priority)})
            print("Tasks loaded from file.")
        else:
            print("No existing task file found. Starting fresh.")

    def save_tasks(self):
        """Save tasks to a file."""
        with open(self.file_name, "w") as file:
            for task in self.tasks:
                file.write(f"{task['task']}|{task['priority']}\n")
        print("Tasks saved to file.")

    def add_task(self, task, priority=3):
        """Add a task to the to-do list with a specified priority (1-5)."""
        if priority < 1 or priority > 5:
            print("Invalid priority! Please choose a priority between 1 (highest) and 5 (lowest).")
        else:
            self.tasks.append({"task": task, "priority": priority})
            self.tasks.sort(key=lambda x: x["priority"])
            print(f"Task '{task}' with priority {priority} added.")

    def remove_task(self, task_number):
        """Remove a task from the to-do list by its number."""
        if 0 < task_number <= len(self.tasks):
            removed_task = self.tasks.pop(task_number - 1)
            print(f"Task '{removed_task['task']}' removed.")
        else:
            print("Invalid task number.")

    def view_tasks(self):
        """View all tasks in the to-do list, sorted by priority."""
        if not self.tasks:
            print("No tasks in the list.")
        else:
            print("Your To-Do List (Sorted by Priority):")
            for i, task in enumerate(self.tasks, 1):
                print(f"{i}. {task['task']} [Priority: {task['priority']}]")

    def clear_tasks(self):
        """Clear all tasks from the to-do list."""
        confirm = input("Are you sure you want to clear all tasks? (y/n): ")
        if confirm.lower() == 'y':
            self.tasks.clear()
            print("All tasks cleared.")
        else:
            print("Clear operation canceled.")

def main():
    todo_list = ToDoList()

    while True:
        print("\n--- To-Do List Menu ---")
        print("1. Add a task")
        print("2. Remove a task")
        print("3. View tasks")
        print("4. Clear all tasks")
        print("5. Save and Exit")
        print("-----------------------")

        choice = input("Enter your choice (1-5): ")

        if choice == '1':
            task = input("Enter the task: ")
            priority = int(input("Enter the priority (1-5, with 1 being the highest): "))
            todo_list.add_task(task, priority)
        elif choice == '2':
            todo_list.view_tasks()
            task_number = int(input("Enter the task number to remove: "))
            todo_list.remove_task(task_number)
        elif choice == '3':
            todo_list.view_tasks()
        elif choice == '4':
            todo_list.clear_tasks()
        elif choice == '5':
            todo_list.save_tasks()
            print("Exiting the To-Do List app. Goodbye!")
            break
        else:
            print("Invalid choice. Please enter a number between 1 and 5.")

if __name__ == "__main__":
    main()