Python Mini-Project: To-Do List Application

Python Mini-Project: To-Do List Application

by

Version 1: Basic Command-Line To-Do List

# Basic Command-Line To-Do List - Version 01

todos = []

while True:
    user_prompt = input('\nType Add, Show, Edit, Complete, Exit: ').strip()

    match user_prompt:
        case 'Add':
            todo = input('Enter a todo to add: ')
            todos.append(todo)
        case 'Show':
            for index, item in enumerate(todos):
                print(f'{index+1}:{item}')
        case 'Edit':
            number = int(input('Enter index of todo to edit like 0,1 and so on: '))
            new_todo = input('Enter new todo to replace: ')
            todos[number-1] = new_todo
        case 'Complete':
            number = int(input('Enter the index to todo to removed since completed: '))
            todos.pop(number-1)
        case 'Exit':
            break
        case _:
            print('''Invalid Input please enter valid input from:
            Add
            Show
            Edit
            Complete
            Exit''')

print('Bye thanks !!!')

Output:

C:\Users\Thebo\PycharmProjects\Learning\venv\Scripts\python.exe C:\Users\Thebo\PycharmProjects\Learning\Project_01.py


Type Add, Show, Edit, Complete, Exit: Add
Enter a todo to add: Go to market
Type Add, Show, Edit, Complete, Exit: Add
Enter a todo to add: Buy Grocery
Type Add, Show, Edit, Complete, Exit: Show
1:Go to market
2:Buy Grocery
Type Add, Show, Edit, Complete, Exit: Edit
Enter index of todo to edit like 0,1 and so on: 2
Enter new todo to replace: Buy Vegetable
Type Add, Show, Edit, Complete, Exit: Show
1:Go to market
2:Buy Vegetable
Type Add, Show, Edit, Complete, Exit: Complete
Enter the index to todo to removed since completed: 1
Type Add, Show, Edit, Complete, Exit: Show
1:Buy Vegetable
Type Add, Show, Edit, Complete, Exit: Exit
Bye thanks !!!

Difference Between match-case and if-else (Simple Explanation)

1. if-else (Conditional Statements)

  • Checks multiple conditions one by one.
  • Used when conditions involve comparisons (>, <, ==, etc.).
  • Works well when dealing with complex logic.

2. match-case (Pattern Matching)

  • Works like a switch statement in other languages.
  • Compares a variable against fixed values or patterns.
  • Best for handling multiple fixed choices (like menu options or commands).

When to Use Each?

✅ Use if-else when:

  • You need to check conditions like greater than, less than, or logical conditions.
  • Example: Checking age to decide eligibility for voting.
age = 18

if age >= 18:
    print("You can vote!")
else:
    print("You cannot vote.")

✅ Use match-case when:

  • You are handling multiple fixed values (like menu choices, error codes, or user inputs).
  • Example: Handling user input in a menu-based system.
choice = "start"

match choice:
    case "start":
        print("Game Started")
    case "pause":
        print("Game Paused")
    case "exit":
        print("Exiting Game")
    case _:
        print("Invalid Choice")

Key Takeaway:

  • Use if-else for conditions that require comparisons.
  • Use match-case when checking fixed values for better readability and efficiency.

# Basic Command-Line To-Do List - Version 02

todos = []

while True:
    user_prompt = input('\nType Add, Show, Edit, Complete, Exit: ').strip()

    match user_prompt:
        case 'Add' | 'add':
            todo = input('Enter a todo to add: ')
            todos.append(todo)
        case 'Show' | 'show':
            for index, item in enumerate(todos):
                print(f'{index+1}:{item}')
        case 'Edit' | 'edit':
            number = int(input('Enter index of todo to edit like 0,1 and so on: '))
            new_todo = input('Enter new todo to replace: ')
            todos[number-1] = new_todo
        case 'Complete' | 'complete':
            number = int(input('Enter the index to todo to removed since completed: '))
            todos.pop(number-1)
        case 'Exit' | 'exit':
            break
        case _:
            print('''Invalid Input please enter valid input from:
            Add
            Show
            Edit
            Complete
            Exit''')

print('Bye thanks !!!')

Output:

C:\Users\Thebo\PycharmProjects\Learning\venv\Scripts\python.exe C:\Users\Thebo\PycharmProjects\Learning\Project_01.py

Type Add, Show, Edit, Complete, Exit: add
Enter a todo to add: KId PTM

Type Add, Show, Edit, Complete, Exit: add
Enter a todo to add: Market

Type Add, Show, Edit, Complete, Exit: show
1:KId PTM
2:Market

Type Add, Show, Edit, Complete, Exit: edit
Enter index of todo to edit like 0,1 and so on: 2
Enter new todo to replace: Doctor

Type Add, Show, Edit, Complete, Exit: complete
Enter the index to todo to removed since completed: 1

Type Add, Show, Edit, Complete, Exit: show
1:Doctor

Type Add, Show, Edit, Complete, Exit: exit
Bye thanks !!!

Process finished with exit code 0

Difference Between | and or in match-case

1. | (Pipe Operator in match-case)

  • Used inside a match-case block to match multiple fixed values in one case.
  • Works only in match-case, not in if-else.
  • Example:
choice = "start"

match choice:
    case "start" | "begin":
        print("Game Started")
    case "pause" | "hold":
        print("Game Paused")
    case "exit" | "quit":
        print("Exiting Game")
    case _:
        print("Invalid Choice")

✅ Output if choice = "begin" → "Game Started" (because "begin" is included in "start" | "begin").

2. or (Logical Operator in if-else)

  • Used in if-else conditions to combine multiple conditions.
  • Works anywhere in Python, including normal condition checks.
  • Example:
choice = "start"

if choice == "start" or choice == "begin":
    print("Game Started")
elif choice == "pause" or choice == "hold":
    print("Game Paused")
elif choice == "exit" or choice == "quit":
    print("Exiting Game")
else:
    print("Invalid Choice")

✅ Output if choice = "begin" → "Game Started" (same result, but written differently).

Version 2: Persistent To-Do List (File-Based Storage)

# Persistent To-Do List (File-Based Storage) - Version 01
# use of file method

while True:
    user_prompt = input('\nType Add, Show, Edit, Complete, Exit: ').strip()

    match user_prompt:
        case 'Add' | 'add':
            todo = input('Enter a todo to add: ') + '\n'

            file = open('todos.txt', 'r')
            todos = file.readlines()
            file.close()

            todos.append(todo)

            file = open('todos.txt', 'w')
            file.writelines(todos)
            file.close()

        case 'Show' | 'show':
            file = open('todos.txt', 'r')
            todos = file.readlines()
            file.close()

            for index, item in enumerate(todos):
                item = item.strip('\n')
                print(f'{index+1}:{item}')
        case 'Edit' | 'edit':
            number = int(input('Enter index of todo to edit like 0,1 and so on: '))
            new_todo = input('Enter new todo to replace: ')
            todos[number-1] = new_todo
        case 'Complete' | 'complete':
            number = int(input('Enter the index to todo to removed since completed: '))
            todos.pop(number-1)
        case 'Exit' | 'exit':
            break
        case _:
            print('''Invalid Input please enter valid input from:
            Add
            Show
            Edit
            Complete
            Exit''')

print('Bye thanks !!!')

Output:

C:\Users\Thebo\PycharmProjects\Learning\venv\Scripts\python.exe C:\Users\Thebo\PycharmProjects\Learning\Project_01.py

Type Add, Show, Edit, Complete, Exit: add
Enter a todo to add: Training

Type Add, Show, Edit, Complete, Exit: show
1:Doctor
2:Market
3:Kid PTM
4:School
5:Training

# Persistent To-Do List (File-Based Storage) - Version 02
# use of with method

while True:
    user_prompt = input('\nType Add, Show, Edit, Complete, Exit: ').strip()

    match user_prompt:
        case 'Add' | 'add':
            todo = input('Enter a todo to add: ') + '\n'

            with open('todos.txt', 'r') as file:
                todos = file.readlines()

            todos.append(todo)

            with open('todos.txt', 'w') as file:
                file.writelines(todos)

        case 'Show' | 'show':

            with open('todos.txt', 'r') as file:
                todos = file.readlines()

            for index, item in enumerate(todos):
                item = item.strip('\n')
                print(f'{index+1}:{item}')
        case 'Edit' | 'edit':
            number = int(input('Enter index of todo to edit like 0,1 and so on: '))

            with open('todos.txt', 'r') as file:
                todos = file.readlines()

            new_todo = input('Enter new todo to replace: ')
            todos[number-1] = new_todo + '\n'

            with open('todos.txt', 'w') as file:
                file.writelines(todos)

        case 'Complete' | 'complete':

            number = int(input('Enter the index to todo to removed since completed: '))

            with open('todos.txt', 'r') as file:
                todos = file.readlines()

            todos.pop(number-1)

            with open('todos.txt', 'w') as file:
                file.writelines(todos)


        case 'Exit' | 'exit':
            break
        case _:
            print('''Invalid Input please enter valid input from:
            Add
            Show
            Edit
            Complete
            Exit''')

print('Bye thanks !!!')

Output:

Type Add, Show, Edit, Complete, Exit: add
Enter a todo to add: Doctor

Type Add, Show, Edit, Complete, Exit: add
Enter a todo to add: Shopping

Type Add, Show, Edit, Complete, Exit: show
1:Doctor
2:Shopping

Type Add, Show, Edit, Complete, Exit: edit
Enter index of todo to edit like 0,1 and so on: 2
Enter new todo to replace: Market

Type Add, Show, Edit, Complete, Exit: show
1:Doctor
2:Market

Type Add, Show, Edit, Complete, Exit: complete
Enter the index to todo to removed since completed: 1

Type Add, Show, Edit, Complete, Exit: show
1:Market

Type Add, Show, Edit, Complete, Exit: exit
Bye thanks !!!

Process finished with exit code 0

# Persistent To-Do List (File-Based Storage) - Version 03
# use of in with if-else

while True:
    user_prompt = input('\nType add, show, edit, complete, exit: ').strip()

    if 'add' in user_prompt:
        todo = user_prompt[4:] + '\n'

        with open('todos.txt', 'r') as file:
            todos = file.readlines()

        todos.append(todo)

        with open('todos.txt', 'w') as file:
            file.writelines(todos)

    elif 'show' in user_prompt:

        with open('todos.txt', 'r') as file:
            todos = file.readlines()

        for index, item in enumerate(todos):
            item = item.strip('\n')
            print(f'{index+1}:{item}')
    elif 'edit' in user_prompt:
        number = int(user_prompt[5:])

        with open('todos.txt', 'r') as file:
            todos = file.readlines()

        new_todo = input('Enter new todo to replace: ')
        todos[number-1] = new_todo + '\n'

        with open('todos.txt', 'w') as file:
            file.writelines(todos)

    elif 'complete' in user_prompt:

        number = int(user_prompt[9:])

        with open('todos.txt', 'r') as file:
            todos = file.readlines()

        todos.pop(number-1)

        with open('todos.txt', 'w') as file:
            file.writelines(todos)
            
    elif 'exit' in user_prompt:
        break
    else:
        print('''Invalid Input please enter valid input from:
        Add
        Show
        Edit
        Complete
        Exit''')

print('Bye thanks !!!')

Output:

Type add, show, edit, complete, exit: show
1:Market
2:testing

Type add, show, edit, complete, exit: add Doctor

Type add, show, edit, complete, exit: show
1:Market
2:testing
3:Doctor

Type add, show, edit, complete, exit: edit 2
Enter new todo to replace: Driving

Type add, show, edit, complete, exit: show
1:Market
2:Driving
3:Doctor

Type add, show, edit, complete, exit: complete 3

Type add, show, edit, complete, exit: show
1:Market
2:Driving

Type add, show, edit, complete, exit: exit
Bye thanks !!!

Process finished with exit code 0

Check input: edit add new task in above

Type add, show, edit, complete, exit: edit add new task

Type add, show, edit, complete, exit: show
1:Market
2:new
3: add new task

Type add, show, edit, complete, exit:

# Persistent To-Do List (File-Based Storage) - Version 04
# use of startswith

while True:
    user_prompt = input('\nType add, show, edit, complete, exit: ').strip()

    if user_prompt.startswith('add'):
        todo = user_prompt[4:] + '\n'

        with open('todos.txt', 'r') as file:
            todos = file.readlines()

        todos.append(todo)

        with open('todos.txt', 'w') as file:
            file.writelines(todos)

    elif user_prompt.startswith('show'):

        with open('todos.txt', 'r') as file:
            todos = file.readlines()

        for index, item in enumerate(todos):
            item = item.strip('\n')
            print(f'{index + 1}:{item}')
    elif user_prompt.startswith('edit'):
        number = int(user_prompt[5:])

        with open('todos.txt', 'r') as file:
            todos = file.readlines()

        new_todo = input('Enter new todo to replace: ')
        todos[number - 1] = new_todo + '\n'

        with open('todos.txt', 'w') as file:
            file.writelines(todos)

    elif user_prompt.startswith('complete'):

        number = int(user_prompt[9:])

        with open('todos.txt', 'r') as file:
            todos = file.readlines()

        todos.pop(number - 1)

        with open('todos.txt', 'w') as file:
            file.writelines(todos)

    elif user_prompt.startswith('exit'):
        break
    else:
        print('''Invalid Input please enter valid input from:
        Add
        Show
        Edit
        Complete
        Exit''')

print('Bye thanks !!!')

Output:

Type add, show, edit, complete, exit: add add new task

Type add, show, edit, complete, exit: show
1:Market
2:new
3: add new task
4:add new task

Type add, show, edit, complete, exit:

Version 3: Error Handling

# Error Handling 

while True:
    user_prompt = input('\nType add, show, edit, complete, exit: ').strip()

    if user_prompt.startswith('add'):
        todo = user_prompt[4:] + '\n'

        with open('todos.txt', 'r') as file:
            todos = file.readlines()

        todos.append(todo)

        with open('todos.txt', 'w') as file:
            file.writelines(todos)

    elif user_prompt.startswith('show'):

        with open('todos.txt', 'r') as file:
            todos = file.readlines()

        for index, item in enumerate(todos):
            item = item.strip('\n')
            print(f'{index + 1}:{item}')
    elif user_prompt.startswith('edit'):
        try:
            number = int(user_prompt[5:])

            with open('todos.txt', 'r') as file:
                todos = file.readlines()

            new_todo = input('Enter new todo to replace: ')
            todos[number - 1] = new_todo + '\n'

            with open('todos.txt', 'w') as file:
                file.writelines(todos)
        except ValueError:
            print('Invalid Input')
            continue
        except IndexError:
            print('Enter valid Index')
            continue

    elif user_prompt.startswith('complete'):
        try:
            number = int(user_prompt[9:])

            with open('todos.txt', 'r') as file:
                todos = file.readlines()

            todos.pop(number - 1)

            with open('todos.txt', 'w') as file:
                file.writelines(todos)
        except ValueError:
            print('Invalid Input')
            continue
        except IndexError:
            print('Enter valid Index')
            continue

    elif user_prompt.startswith('exit'):
        break
    else:
        print('''Invalid Input please enter valid input from:
        Add
        Show
        Edit
        Complete
        Exit''')

print('Bye thanks !!!')

Output:

Type add, show, edit, complete, exit: edit test
Invalid Input

Type add, show, edit, complete, exit: edit 123
Enter new todo to replace: test
Enter valid Index

Type add, show, edit, complete, exit: complete one
Invalid Input

Type add, show, edit, complete, exit: complete 123
Enter valid Index

Type add, show, edit, complete, exit: show
1:Market
2:new
3: add new task
4:add new task
5:testing123

Type add, show, edit, complete, exit: exit
Bye thanks !!!

Understanding the Need for continue in while True

Let’s consider two cases:

🔹 Case 1: No continue – The loop naturally continues

If the loop naturally continues after handling an exception, you don’t need continue:

while True:
    try:
        num = int(input("Enter a number: "))  # If user enters "abc", it raises ValueError
        print(f"You entered: {num}")
    except ValueError:
        print("Invalid input! Please enter a number.")  # The loop continues without `continue`

✅ Why it works?

  • After handling the exception, the loop moves to the next iteration automatically.

🔹 Case 2: Using continue to Explicitly Restart the Loop

You use continue when you want to immediately restart the loop without executing further code in the current iteration:

while True:
    try:
        num = int(input("Enter a number: "))
    except ValueError:
        print("Invalid input! Try again.")
        continue  # Skips the next line and goes back to input prompt
    print(f"You entered: {num}")

✅ Why use continue?

  • Without continue, if an exception occurs, Python would still execute the next line (print(f"You entered: {num}")), which could cause errors.
  • continue forces the loop to restart immediately, skipping unnecessary execution.

🔹 When Should You Use continue?

✔ Use continue if there is additional code after the try-except block that you want to skip when an exception occurs.
❌ Don’t use continue if the loop naturally continues as expected.

Where to Place continue in Multiple except Blocks?

✅ Option 1: Use continue in Each except Block (if all errors should restart the loop)

If every exception should restart the loop, put continue in all except blocks:

while True:
    try:
        num = int(input("Enter a number: "))
        result = 100 / num  # Possible ZeroDivisionError
    except ValueError:
        print("Invalid input! Please enter a number.")
        continue  # Restart loop
    except ZeroDivisionError:
        print("Cannot divide by zero! Try again.")
        continue  # Restart loop
    except Exception:
        print("Something went wrong!")
        continue  # Restart loop
    print(f"Result: {result}")  # Runs only if no exception occurs

✅ Why?

  • If an exception occurs, the loop restarts immediately, skipping the print(f"Result: {result}") statement.

✅ Option 2: Use continue Only in Specific except Blocks

If only some exceptions should restart the loop while others allow the program to continue, put continue selectively:

while True:
    try:
        num = int(input("Enter a number: "))
        result = 100 / num
    except ValueError:
        print("Invalid input! Please enter a number.")
        continue  # Restart loop
    except ZeroDivisionError:
        print("Cannot divide by zero! Try again.")
        continue  # Restart loop
    except Exception:
        print("Something unexpected happened!")  # No continue here, so loop continues normally
    print(f"Result: {result}")  # This runs unless a ValueError or ZeroDivisionError occurs

✅ Why?

  • continue is used only when we want to restart the loop.
  • If a general exception (Exception) occurs, we don’t restart the loop—execution continues normally.

🔹 Key Takeaways

✔ Use continue in each except block where you want to restart the loop.
✔ Don’t use continue in except blocks where you want execution to proceed normally.
✔ The last except block doesn’t need continue unless you specifically want to restart the loop.

Version 4: Custom Functions

# Custom Functions - Removed redundant codes v_01

def get_todos():
    with open('todos.txt', 'r') as file_local:
        todos_local = file_local.readlines()
        return todos_local


while True:
    user_prompt = input('\nType add, show, edit, complete, exit: ').strip()

    if user_prompt.startswith('add'):
        todo = user_prompt[4:] + '\n'

        todos = get_todos()

        todos.append(todo)

        with open('todos.txt', 'w') as file:
            file.writelines(todos)

    elif user_prompt.startswith('show'):

        todos = get_todos()

        for index, item in enumerate(todos):
            item = item.strip('\n')
            print(f'{index + 1}:{item}')
    elif user_prompt.startswith('edit'):
        try:
            number = int(user_prompt[5:])

            todos = get_todos()

            new_todo = input('Enter new todo to replace: ')
            todos[number - 1] = new_todo + '\n'

            with open('todos.txt', 'w') as file:
                file.writelines(todos)
        except ValueError:
            print('Invalid Input')
            continue
        except IndexError:
            print('Enter valid Index')
            continue

    elif user_prompt.startswith('complete'):
        try:
            number = int(user_prompt[9:])

            todos = get_todos('todos.txt')

            todos.pop(number - 1)

            with open('todos.txt', 'w') as file:
                file.writelines(todos)
        except ValueError:
            print('Invalid Input')
            continue
        except IndexError:
            print('Enter valid Index')
            continue

    elif user_prompt.startswith('exit'):
        break
    else:
        print('''Invalid Input please enter valid input from:
        Add
        Show
        Edit
        Complete
        Exit''')

print('Bye thanks !!!')

Output:

Type add, show, edit, complete, exit: show
1:Market
2:new
3: add new task
4:add new task
5:testing123

Type add, show, edit, complete, exit: add testing01

Type add, show, edit, complete, exit: add testing 02

Type add, show, edit, complete, exit: show
1:Market
2:new
3: add new task
4:add new task
5:testing123
6:testing01
7:testing 02

# Custom Functions - Removed redundant codes v_02

def get_todos(filepath):
    with open(filepath, 'r') as file_local:
        todos_local = file_local.readlines()
        return todos_local


def write_todos(filepath, todos_arg):
    with open(filepath, 'w') as file:
        file.writelines(todos_arg)


while True:
    user_prompt = input('\nType add, show, edit, complete, exit: ').strip()

    if user_prompt.startswith('add'):
        todo = user_prompt[4:] + '\n'

        todos = get_todos('todos.txt')

        todos.append(todo)

        write_todos('todos.txt', todos)

    elif user_prompt.startswith('show'):

        todos = get_todos('todos.txt')

        for index, item in enumerate(todos):
            item = item.strip('\n')
            print(f'{index + 1}:{item}')
    elif user_prompt.startswith('edit'):
        try:
            number = int(user_prompt[5:])

            todos = get_todos('todos.txt')

            new_todo = input('Enter new todo to replace: ')
            todos[number - 1] = new_todo + '\n'

            write_todos('todos.txt', todos)

        except ValueError:
            print('Invalid Input')
            continue
        except IndexError:
            print('Enter valid Index')
            continue

    elif user_prompt.startswith('complete'):
        try:
            number = int(user_prompt[9:])

            todos = get_todos('todos.txt')

            todos.pop(number - 1)

            write_todos('todos.txt', todos)

        except ValueError:
            print('Invalid Input')
            continue
        except IndexError:
            print('Enter valid Index')
            continue

    elif user_prompt.startswith('exit'):
        break
    else:
        print('''Invalid Input please enter valid input from:
        Add
        Show
        Edit
        Complete
        Exit''')

print('Bye thanks !!!')

Ouput:

Type add, show, edit, complete, exit: show
1:Doctor Visit
2:Shopping

Type add, show, edit, complete, exit: add Vegetable

Type add, show, edit, complete, exit: show
1:Doctor Visit
2:Shopping
3:Vegetable

Type add, show, edit, complete, exit: complete 2

Type add, show, edit, complete, exit: show
1:Doctor Visit
2:Vegetable

Type add, show, edit, complete, exit: exit
Bye thanks !!!

Process finished with exit code 0

Version 5: Organizing the Code in Modules

# Organizing the Code in Modules v_01

from functions import get_todos, write_todos

while True:
    user_prompt = input('\nType add, show, edit, complete, exit: ').strip()

    if user_prompt.startswith('add'):
        todo = user_prompt[4:] + '\n'

        todos = get_todos('todos.txt')

        todos.append(todo)

        write_todos('todos.txt', todos)

    elif user_prompt.startswith('show'):

        todos = get_todos('todos.txt')

        for index, item in enumerate(todos):
            item = item.strip('\n')
            print(f'{index + 1}:{item}')
    elif user_prompt.startswith('edit'):
        try:
            number = int(user_prompt[5:])

            todos = get_todos('todos.txt')

            new_todo = input('Enter new todo to replace: ')
            todos[number - 1] = new_todo + '\n'

            write_todos('todos.txt', todos)

        except ValueError:
            print('Invalid Input')
            continue
        except IndexError:
            print('Enter valid Index')
            continue

    elif user_prompt.startswith('complete'):
        try:
            number = int(user_prompt[9:])

            todos = get_todos('todos.txt')

            todos.pop(number - 1)

            write_todos('todos.txt', todos)

        except ValueError:
            print('Invalid Input')
            continue
        except IndexError:
            print('Enter valid Index')
            continue

    elif user_prompt.startswith('exit'):
        break
    else:
        print('''Invalid Input please enter valid input from:
        Add
        Show
        Edit
        Complete
        Exit''')

print('Bye thanks !!!')

Output:

Type add, show, edit, complete, exit: show
1:Doctor Visit
2:Vegetable

Type add, show, edit, complete, exit: add Dentist

Type add, show, edit, complete, exit: show
1:Doctor Visit
2:Vegetable
3:Dentist

# Organizing the Code in Modules v_02

import functions

while True:
    user_prompt = input('\nType add, show, edit, complete, exit: ').strip()

    if user_prompt.startswith('add'):
        todo = user_prompt[4:] + '\n'

        todos = functions.get_todos('todos.txt')

        todos.append(todo)

        functions.write_todos('todos.txt', todos)

    elif user_prompt.startswith('show'):

        todos = functions.get_todos('todos.txt')

        for index, item in enumerate(todos):
            item = item.strip('\n')
            print(f'{index + 1}:{item}')
    elif user_prompt.startswith('edit'):
        try:
            number = int(user_prompt[5:])

            todos = functions.get_todos('todos.txt')

            new_todo = input('Enter new todo to replace: ')
            todos[number - 1] = new_todo + '\n'

            functions.write_todos('todos.txt', todos)

        except ValueError:
            print('Invalid Input')
            continue
        except IndexError:
            print('Enter valid Index')
            continue

    elif user_prompt.startswith('complete'):
        try:
            number = int(user_prompt[9:])

            todos = functions.get_todos('todos.txt')

            todos.pop(number - 1)

            functions.write_todos('todos.txt', todos)

        except ValueError:
            print('Invalid Input')
            continue
        except IndexError:
            print('Enter valid Index')
            continue

    elif user_prompt.startswith('exit'):
        break
    else:
        print('''Invalid Input please enter valid input from:
        Add
        Show
        Edit
        Complete
        Exit''')

print('Bye thanks !!!')

Output:

Type add, show, edit, complete, exit: show
1:Doctor Visit
2:Vegetable
3:Dentist

Type add, show, edit, complete, exit: add Marketing

Type add, show, edit, complete, exit: show
1:Doctor Visit
2:Vegetable
3:Dentist
4:Marketing

# Organizing the Code in Modules v_03

from module import functions

while True:
    user_prompt = input('\nType add, show, edit, complete, exit: ').strip()

    if user_prompt.startswith('add'):
        todo = user_prompt[4:] + '\n'

        todos = functions.get_todos('todos.txt')

        todos.append(todo)

        functions.write_todos('todos.txt', todos)

    elif user_prompt.startswith('show'):

        todos = functions.get_todos('todos.txt')

        for index, item in enumerate(todos):
            item = item.strip('\n')
            print(f'{index + 1}:{item}')
    elif user_prompt.startswith('edit'):
        try:
            number = int(user_prompt[5:])

            todos = functions.get_todos('todos.txt')

            new_todo = input('Enter new todo to replace: ')
            todos[number - 1] = new_todo + '\n'

            functions.write_todos('todos.txt', todos)

        except ValueError:
            print('Invalid Input')
            continue
        except IndexError:
            print('Enter valid Index')
            continue

    elif user_prompt.startswith('complete'):
        try:
            number = int(user_prompt[9:])

            todos = functions.get_todos('todos.txt')

            todos.pop(number - 1)

            functions.write_todos('todos.txt', todos)

        except ValueError:
            print('Invalid Input')
            continue
        except IndexError:
            print('Enter valid Index')
            continue

    elif user_prompt.startswith('exit'):
        break
    else:
        print('''Invalid Input please enter valid input from:
        Add
        Show
        Edit
        Complete
        Exit''')

print('Bye thanks !!!')

Output:

Type add, show, edit, complete, exit: show
1:Doctor Visit
2:Vegetable
3:Dentist
4:Marketing

Type add, show, edit, complete, exit: add Outing

Type add, show, edit, complete, exit: sho
Invalid Input please enter valid input from:
Add
Show
Edit
Complete
Exit

Type add, show, edit, complete, exit: show
1:Doctor Visit
2:Vegetable
3:Dentist
4:Marketing
5:Outing

# Organizing the Code in Modules v_04 (Add time stamp)

import functions
import time

now = time.strftime('%b %d, %Y %H:%M:%S')
print('It is', now)

while True:
    user_prompt = input('\nType add, show, edit, complete, exit: ').strip()

    if user_prompt.startswith('add'):
        todo = user_prompt[4:] + '\n'

        todos = functions.get_todos('todos.txt')

        todos.append(todo)

        functions.write_todos('todos.txt', todos)

    elif user_prompt.startswith('show'):

        todos = functions.get_todos('todos.txt')

        for index, item in enumerate(todos):
            item = item.strip('\n')
            print(f'{index + 1}:{item}')
    elif user_prompt.startswith('edit'):
        try:
            number = int(user_prompt[5:])

            todos = functions.get_todos('todos.txt')

            new_todo = input('Enter new todo to replace: ')
            todos[number - 1] = new_todo + '\n'

            functions.write_todos('todos.txt', todos)

        except ValueError:
            print('Invalid Input')
            continue
        except IndexError:
            print('Enter valid Index')
            continue

    elif user_prompt.startswith('complete'):
        try:
            number = int(user_prompt[9:])

            todos = functions.get_todos('todos.txt')

            todos.pop(number - 1)

            functions.write_todos('todos.txt', todos)

        except ValueError:
            print('Invalid Input')
            continue
        except IndexError:
            print('Enter valid Index')
            continue

    elif user_prompt.startswith('exit'):
        break
    else:
        print('''Invalid Input please enter valid input from:
        Add
        Show
        Edit
        Complete
        Exit''')

print('Bye thanks !!!')

Output:

It is Feb 19, 2025 13:02:21

Type add, show, edit, complete, exit: show
1:Doctor Visit
2:Vegetable
3:Dentist
4:Marketing
5:Outing

# Organizing the Code in Modules v_05 (Default argument in module)

import functions
import time

now = time.strftime('%b %d, %Y %H:%M:%S')
print('It is', now)

while True:
    user_prompt = input('\nType add, show, edit, complete, exit: ').strip()

    if user_prompt.startswith('add'):
        todo = user_prompt[4:] + '\n'

        todos = functions.get_todos()

        todos.append(todo)

        functions.write_todos(todos)

    elif user_prompt.startswith('show'):

        todos = functions.get_todos()

        for index, item in enumerate(todos):
            item = item.strip('\n')
            print(f'{index + 1}:{item}')
    elif user_prompt.startswith('edit'):
        try:
            number = int(user_prompt[5:])

            todos = functions.get_todos()

            new_todo = input('Enter new todo to replace: ')
            todos[number - 1] = new_todo + '\n'

            functions.write_todos(todos)

        except ValueError:
            print('Invalid Input')
            continue
        except IndexError:
            print('Enter valid Index')
            continue

    elif user_prompt.startswith('complete'):
        try:
            number = int(user_prompt[9:])

            todos = functions.get_todos()

            todos.pop(number - 1)

            functions.write_todos(todos)

        except ValueError:
            print('Invalid Input')
            continue
        except IndexError:
            print('Enter valid Index')
            continue

    elif user_prompt.startswith('exit'):
        break
    else:
        print('''Invalid Input please enter valid input from:
        Add
        Show
        Edit
        Complete
        Exit''')

print('Bye thanks !!!')
FILEPATH = 'todos.txt'

def get_todos(filepath=FILEPATH):
    with open(filepath, 'r') as file_local:
        todos_local = file_local.readlines()
        return todos_local


def write_todos(todos_arg, filepath=FILEPATH):
    with open(filepath, 'w') as file:
        file.writelines(todos_arg)


# print('I am outside')

if __name__ == '__main__':
    print('I am inside')
    print(get_todos('todos.txt'))

Understanding if __name__ == "__main__":

This special condition in Python is used to control whether a script runs when executed directly or when imported as a module in another script.

🔹 What Does __name__ Mean?

In every Python script, Python automatically creates a special variable called __name__.

  • If the script is run directly, __name__ is set to "__main__".
  • If the script is imported into another script, __name__ is set to the module name instead.

✅ Basic Example: Running Directly vs. Importing

📌 Case 1: When Running the Script Directly

# my_script.py
print("This runs always!")

if __name__ == "__main__":
    print("This runs only when executed directly!")

📌 Output when you run my_script.py directly:

This runs always!
This runs only when executed directly!

✅ Why?

  • Since the script is executed directly, __name__ is "__main__".

📌 Case 2: When Importing the Script

Let’s import my_script.py into another script:

# another_script.py
import my_script
print("Hello from another_script.py!")

📌 Output when running another_script.py:

This runs always!
Hello from another_script.py!

✅ Why?

  • The first print statement in my_script.py executes because the file is imported.
  • But the code inside if __name__ == "__main__": does not run because __name__ is "my_script" (not "__main__").

🔹 Why Use if __name__ == "__main__":?

  1. Prevents certain code from running when imported.
  2. Useful for defining reusable modules (functions & classes remain accessible when imported).
  3. Commonly used in Python scripts that have a mix of functions and executable code.

✅ Example: Using It in a Function

def greet():
    print("Hello, World!")

if __name__ == "__main__":
    greet()  # Runs only if executed directly
  • If run directly → It prints "Hello, World!".
  • If imported → The function greet() is available, but it doesn’t execute automatically.

🔹 Summary

✔ if __name__ == "__main__": ensures that some code only runs when the script is executed directly.
✔ Prevents unintended execution when the script is imported into another module.
✔ Best practice when writing reusable scripts and modules.

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