Practicing using a "flag": please point in right direction

[magsloo]

I'm currently going through the Python Crash Course and I'm on Chapter 7. I'm attempting to use an active variable to control how long the loop runs.

prompt = "\nWhat is your age?"
prompt += "\n(Enter 'quit' when you are finished.)" 

active = True 
while active: 
    age = input(prompt) 
    
    if age == 'quit': 
        active = False 
    age = int(age)
    if age < 3:
        print("\nYour ticket is free!") 
    elif age < 12: 
        print("\nYour ticket is 10$!") 
    else:
        print("\nYour ticket is 15$!") 
        

The above works until I enter quit.

Error:
Traceback (most recent call last):
  File "parrot.py", line 10, in <module>
    age = int(age)
ValueError: invalid literal for int() with base 10: 'quit'

I know that this is because I change age data type to an integer data type so I can use the comparison operators However, quit is not an int. I feel like maybe this is a matter of placement? I've tried different placements (before the if age == 'quit') but it's still not working. Could someone please point me in the right direction? Thank you!

[Gribouillis]

The problem is that after running line 9, the code goes on with line 10. Why don't you simply replace line 9 with the break statement?

[buran]

it's more common to skip the flag

while True: 
    age = input("\nWhat is your age?\n(Enter 'quit' when you are finished.)" ) 
    if age == 'quit': 
        break
    age = int(age)
    if age < 3:
        print("\nYour ticket is free!") 
    elif age < 12: 
        print("\nYour ticket is 10$!") 
    else:
        print("\nYour ticket is 15$!") 

[magsloo]

The problem is that after running line 9, the code goes on with line 10. Why don't you simply replace line 9 with the break statement?

Hi! So I actually have that already done but I'm trying to practice using a flag (following the practice problems in the book) so I'm attempting to revise my code so it adds a flag.

Here is my code with a break:

prompt = "\nWhat is your age?"
prompt += "\n(Enter 'quit' when you are finished.)" 

while True:
    age = input(prompt) 
    
    if age == 'quit': 
        break
    age = int(age)
    if age < 3:
        print("\nYour ticket is free!") 
    elif age < 12: 
        print("\nYour ticket is 10$!") 
    else:
        print("\nYour ticket is 15$!") 
        

---

it's more common to skip the flag

while True: age = input("\nWhat is your age?\n(Enter 'quit' when you are finished.)" ) if age == 'quit': break age = int(age) if age < 3: print("\nYour ticket is free!") elif age < 12: print("\nYour ticket is 10$!") else: print("\nYour ticket is 15$!") 

Hi sorry! First, ty for your reply! I just posted below but I do already have a version of this with break. I'm just trying to practicing using a flag now. In addition, what do you mean by it's more common to skip a flag? Flags are not commonly used when coding? Is that a correct understanding of what you said? Thank you so much again!

[MvGulik]

For a case without using a break one would generally use only one main if block (to prevent potential unintended fall-trough into the other if's).

In your initial case that could have been done by using the else option of the if age == 'quit': condition.
ie:

#...
active = True 
while active: 
    age = input(prompt)

    if age == 'quit':
        active = False

    else: ## do stuff if age was not equal to 'quit'.
        age = int(age)

        if age < 3:
            print("\nYour ticket is free!")
        elif age < 12:
            print("\nYour ticket is 10$!") 
        else:
            print("\nYour ticket is 15$!")

[perfringo]

I'm trying to practice using a flag (following the practice problems in the book) so I'm attempting to revise my code so it adds a flag.

I personally would recommend not to practice using flags. In majority of cases there is 'pythonic' way to have concise and more readable code without flag.