Unable to return variable from one function and use it in another function

Question

I am attempting to return a list of coins from one function to another, then split it and sum the results. I'm trying to return one list from a function, then use it in the next. I put the list in as a positional argument in the main function, but it says it isn't defined. I have a return statement in the function, so I'm not sure what's wrong.

import random
import time
import math



CORRECT_LIST = ['Great job!', 'You did it!', 'Right answer.', 'Awesome!']
INCORRECT_LIST = ['Not quite.', 'Try again.', 'Keep trying.', 'Check your math.']


#Controls all other functions
def main():

    choose_coins()
    coin_tokens = choose_coins()

#Choose the number and type of coins
def choose_coins():

    coin_tokens = []

    #List of coins to pick from
    coin_list = ['Penny', 'Nickel', 'Dime', 'Quarter']
    
    #Choose the number of coins
    num_coins = random.randint(2,4)

    #Add chosen coins to a list
    for i in range(num_coins):


        coins_to_be_counted = random.choice(coin_list)

        coin_tokens.append(coins_to_be_counted)

   
    print(coin_tokens)

    return coin_tokens


    


#Add coins using tokens from coin_tokens list
def add_coins(coin_tokens):


    #Iterate through coin_tokens list
    for i in coin_tokens:

        if token == 'Penny':
            coin_total += 1

        elif token == 'Nickel':
            coin_total += 5

        elif token == 'Dime':
            coin_total += 10
    
        elif token == 'Quarter':
            coin_total += 25

        coin_total = 0
        
    print(coin_total)



#Starts the Program
if __name__ == "__main__":
    main()

A return statement doesn't magically make a variable name available in the scope of the caller of the function; indeed, you can return things other than a variable, such as a literal or expression. You have to explicitly make use of the function's value at the point of the call - something like somevar = choose_coins() for example. — jasonharper
– jasonharper, Commented Feb 7, 2022 at 15:06
@BenB It doesn't make sense to call split() on a list. The initial lines of coin_tokens.split() should simply be erased. — Ben Grossmann
– Ben Grossmann, Commented Feb 7, 2022 at 15:10

jsfehler · Accepted Answer · 2022-02-07 15:05:53Z

1

You're returning a value, but you're not assigning it to a variable.

my_coins = choose_coins()
add_coins(my_coins)

answered Feb 7, 2022 at 15:05

jsfehler

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Comments

helloWORLD · Accepted Answer · 2022-02-07 15:19:17Z

You have made a lot of minor errors. For instance, using 'i' in the for loop but checking condition on a undefined variable 'token', calling a function with return value and not assigning a variable for it.

Please check the following code. I have made a changes, it should work now.

import random
import time
import math

CORRECT_LIST = ['Great job!', 'You did it!', 'Right answer.', 'Awesome!']
INCORRECT_LIST = ['Not quite.', 'Try again.', 'Keep trying.', 'Check your math.']


#Controls all other functions
def main():

    coins = choose_coins()
    add_coins(coins)

    
#Choose the number and type of coins
def choose_coins():
    coin_tokens = []
    #List of coins to pick from
    coin_list = ['Penny', 'Nickel', 'Dime', 'Quarter']
    #Choose the number of coins
    num_coins = random.randint(2,4)
    #Add chosen coins to a list
    for i in range(num_coins):
        coins_to_be_counted = random.choice(coin_list)
        coin_tokens.append(coins_to_be_counted)
    print(coin_tokens)
    
    return coin_tokens

#Add coins using tokens from coin_tokens list
def add_coins(coin_tokens):
    coin_total = 0
    for token in coin_tokens:
        if token == 'Penny':
            coin_total += 1
        elif token == 'Nickel':
            coin_total += 5
        elif token == 'Dime':
            coin_total += 10
        elif token == 'Quarter':
            coin_total += 25
            
    print(coin_total)
    


#Starts the Program
if __name__ == "__main__":
    main()

Mario · Accepted Answer · 2022-02-07 15:05:31Z

0

You could try doing:

def main():
    add_coins(choose_coins())

instead of

def main():

    choose_coins()
    add_coins(coin_tokens)

In your version the functions aren't connected and you're probably getting an error like NameError: name 'coin_tokens' is not defined

answered Feb 7, 2022 at 15:05

Mario

5833 silver badges21 bronze badges

Comments

Dan Monego · Accepted Answer · 2022-02-07 15:08:00Z

0

Your return statement needs to be fixed. return [coin_tokens] returns a list with your list inside it. So this:

    return[coin_tokens]

should be:

    return coin_tokens

Then, assign the return value:

coin_tokens = choose_coins()

answered Feb 7, 2022 at 15:08

Dan Monego

10.2k6 gold badges42 silver badges78 bronze badges

1 Comment

BenB Over a year ago

I edited the post with the updated code, thanks for the assist.

Amal K · Accepted Answer · 2022-02-07 15:27:22Z

There are multiple problems with your code. The syntax to call a function is as follows:

return_value = function_name(arguments)

You are calling choose_coins() but not storing the return value:

def main():

    coin_tokens = choose_coins()
    add_coins(coin_tokens)

Or even:

 add_coins(choose_coins())

When you write:

return[coin_tokens]

It is wrapping your coin_tokens which is already a list into another list. Change it to:

return coin_tokens

You do not need this line; it has no effect:

coin_tokens.split()
print(coin_tokens)

You should use token instead of i in the for loop. And have not initialized coin_total to 0 before the loop:

def add_coins(coin_tokens):
    
    print(coin_tokens)
    # Initialize to 0
    coin_total = 0

    #Iterate through coin_tokens list
    for token in coin_tokens:
        if token == 'Penny':
            coin_total += 1

        elif token == 'Nickel':
            coin_total += 5

        elif token == 'Dime':
            coin_total += 10
    
        elif token == 'Quarter':
            coin_total += 25

        
    print(coin_total)

And it would be a better idea to return coin_total:

return coin_total

And use it like this in main:

coin_tokens = choose_coins()
total = add_coins(coin_tokens)
print(f"Total is {total}")

Ben Grossmann · Accepted Answer · 2022-02-07 15:34:14Z

You might the following rewrite of your code to be interesting.

import random
import time
import math

CORRECT_LIST = ['Great job!', 'You did it!', 'Right answer.', 'Awesome!']
INCORRECT_LIST = ['Not quite.', 'Try again.', 'Keep trying.', 'Check your math.']
COIN_LIST = ['Penny', 'Nickel', 'Dime', 'Quarter']
VALUE = {'Penny':1,'Nickel':5,'Dime':10,'Quarter':25}

def main():
    coin_tokens = choose_coins()
    add_coins(coin_tokens)

#Choose the number and type of coins
def choose_coins():

    #List of coins to pick from
    global COIN_LIST

    #Choose the number of coins
    num_coins = random.randint(2,4)
    coin_tokens = random.choices(COIN_LIST,k=num_coins)
    
    print(coin_tokens)
    return coin_tokens
    


#Add coins using tokens from coin_tokens list
def add_coins(coin_tokens):

    print(coin_tokens)
    global VALUE 
    coin_total = sum(VALUE[coin] for coin in coin_tokens)
    
    print(coin_total)


main()

#Starts the Program
if __name__ == "__main__":
    main()

You could further shorten the code to the following.

import random
import time
import math

CORRECT_LIST = ['Great job!', 'You did it!', 'Right answer.', 'Awesome!']
INCORRECT_LIST = ['Not quite.', 'Try again.', 'Keep trying.', 'Check your math.'] 
VALUE = {'Penny':1,'Nickel':5,'Dime':10,'Quarter':25}

def main():
    coin_tokens = choose_coins()
    print(coin_tokens)
    total = add_coins(coin_tokens)
    print(total)

#Choose the number and type of coins
def choose_coins():
    return random.choices(list(VALUE),k=random.randint(2,4))

#Add coins using tokens from coin_tokens list
def add_coins(coin_tokens):
    return sum(VALUE[coin] for coin in coin_tokens)

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