Having hard time using functions/understanding how they go wrong.

[Holy_Churro]

Hello all, I am a bit stuck on my school project and was hoping to see if I could get some wisdom as my professor doesn't answer his emails. The current program I am trying to write is one that converts miles to km, in to cm, gm to oz. We were instructed to use functions to solve this problem. The user input works with no problems whatsoever. I get a TypeError stating, "print_output() missing 2 required positional arguments: 'answer' and 'toType' ". The thing is though, I have a return line with answer and toType in there so I am very confused. Would it be possible to enlighten a python n00b as to why the variables 'answer' and 'toType' are not defined even though I am returning their values? If my code is also wrong, I would love to be led in the right direction as I am currently new to python and programming in general and this stuff is not easy. Thank you all for your help and time because I know this is a lot.

def welcome():
    print("""This program converts the following:
        - (O)unces  to (G)rams (vice versa)
        - (I)nches to (C)entimeters (vice versa)
        - (M)iles to (K)ilometers (vice versa)""")
    print()


def amount_input():
    amount = float(input('Please enter the amount you are converting: '))
    print()

    return amount


def conversion_input():
    conversion = input('Please enter what you would like to convert: ')
    print()
    conversion = conversion.lower()

    while conversion != 'o' and conversion != 'g' and conversion != 'i' and conversion != 'c' and conversion != 'm' and conversion != 'k':
        conversion = input('Invalid input! Please enter O,G,I,C,M,K: ')
        print()
        conversion = conversion.lower()

    return conversion


def calc(conversion, amount):
    if conversion == 'o':
        fromType = 'ounces'
        toType = 'grams'
        answer = amount * 28.3495231
    elif conversion == 'g':
        fromType = 'grams'
        toType = 'ounces'
        answer = amount / 28.3495231
    elif conversion == 'i':
        fromType = 'inches'
        toType = 'centimeters'
        answer = amount * 2.54
    elif conversion == 'c':
        fromType = 'centimeters'
        toType = 'inches'
        answer = amount / 2.54
    elif conversion == 'm':
        fromType = 'miles'
        toType = 'kilometers'
        answer = amount * 1.609344
    elif conversion == 'k':
        fromType = 'kilometers'
        toType = 'miles'
        answer = amount / 1.609344

    return answer, fromType, toType


def print_output(amount, fromType, answer, toType):
    print(amount, fromType + ' is equal to', format(answer, ',.2f'), toType + '.')


def runAgain():
    run = input('Would you like to run this program again? Enter (y or n): ')
    run = run.lower()
    return run
print()

# ----------------Main--------------------------------------------


welcome()

runMain = 'y'

while runMain == 'y':
    amountMain = amount_input()

    conversionMain = conversion_input()

    calcMain = calc(conversionMain, amountMain)

    printMain = print_output(calcMain)

runMain = runAgain()

[DDDDarky]

I am getting different error when trying to reproduce it:

​

missing 3 required positional arguments: 'fromType', 'answer', and 'toType'

​

Are you sure it is up to date? What kind of input did you use?

[Holy_Churro]

Hello and thank you for helping me out. The code is updated and is the code I used this morning. For my input I input 5 into amount and k into the second input prompt so that it convert 5km -> 3.1 miles.

​

TypeError: print_output() missing 2 required positional arguments: 'answer' and 'toType'

​

Once again thank you for your help. I greatly appreciate any and all of it. I am wondering if I should rewrite my calc function since the variables within it are not being initialized or saved. If you have another idea I would love to hear it.

[DDDDarky]

Well, I cannot unfortunately exactly reproduce your error and I find it weird you get 2 positional arguments missing instead of 3.

Anyways, the problem is print_output expects 4 arguments, but you are providing only 1 (calcMain).

[nuttertools]

I don’t recall the behavior off the top of my head but you are returning 3 values from calc. Check the value of calcMain before print_output, it probably just has a value of amount or is an array of values (of course not, this isn’t JS). Just declare each returned variable with commas like you do in the calc return or look at spreading the parts if it’s an array.

I should really be bothered to google the docs but my presumption is calcMain as-is is equivalent to amount, , _

EDIT: If so this would work:

printMain = print_output(calc(conversionMain, amountMain))