Error in calculator program using python. NameError

Question

i get the error traceback (most recent call last): File "main.py", line 64, in print(f" {num_1} {operation} {num_2} = {answer}") NameError: name 'answer' is not defined

idk why, tho. this code was working very well, so i didnt touch it. but as sson as i tried other mathematical operations it broke.

#inputs and stuff VV
num_1 = input("What's Your First Number?:  ")
operation = input(" + \n - \n * \n / \n Pick An Operation:  ")
num_2 = input("What's Your next Number?:  ")


#functions
def addition():
  answer = int(num_1) + int(num_2)

def subtraction():
  answer = int(num_1) - int(num_2)

def multiplication():
  answer = int(num_1) * int(num_2)

def division():
  answer = int(num_1) / int(num_2)

def continue_prog():
  print(answer)
  operation = input(" + \n - \n * \n / \n Pick An Operation:  ")
  new_num_2 = input("What's Your next Number?:  ")
  print(f" {answer} {operation} {new_num_2} = {answer}")

def Continue_or_not():
  continue_or_not = input(f"Typer 'Y' to Continue Calculating With {answer}. \n Or Type 'N' To   Begin New Operation \n Or 'C' To Close The Calculator: ")

  if continue_or_not == "Y":
    continue_prog()

  if continue_or_not == "N":
    clear()
    answer = 0
    num_1 = input("What's Your First Number?:  ")
    operation = input(" + \n - \n * \n / \n Pick An Operation:  ")
    num_2 = input("What's Your next Number?:  ")

  else:
    exit()
  
  
  
  

#computer checking which operation was picked
def chosen_operation():
  if operation == '+':
    addition()
  if operation == "-":
    subtraction()
  if operation == "*":
    multiplication()
  if operation == "/":
    division()

chosen_operation()


#Actual Code
print(f" {num_1} {operation} {num_2} = {answer}")
continue_or_not = input(f"Typer 'Y' to Continue Calculating With {answer}. \nOr Type 'N' To Begin New Operation \nOr 'C' To Close The Calculator: \n")

if continue_or_not == "Y":
  continue_prog()

if continue_or_not == "N":
  clear()

else:
  exit()

please help, i need this so i can impress my mother.

i tried deleted a variable i had, which was (answer = 0 ) so new variables can be put in the empty answer variable. but it broke the code more

answer needs to be returned from the operation functions and give as input to continue_prog — darth baba, Sep 02 '23 at 16:39
https://stackoverflow.com/questions/7129285/what-is-the-purpose-of-the-return-statement-how-is-it-different-from-printing — Tzane, Sep 02 '23 at 17:25
hey Tzane, i know the diffrence, but i just learnt about the return function today, so excuse me for using the print function too much. — A.H Moussa, Sep 02 '23 at 17:28

Frederick · Accepted Answer · 2023-09-02T17:21:58.553

-1

In your code you define new 'answer' variable in each function again so the answer variable doesn't refer to the global 'answer' variable, to make the answer variable refer to the global one you can add global keyword like this

def addition():
  global answer 
  answer = int(num_1) + int(num_2)

def subtraction():
  global answer 
  answer = int(num_1) - int(num_2)

def multiplication():
  global answer 
  answer = int(num_1) * int(num_2)

def division():
  global answer 
  answer = int(num_1) / int(num_2)

and also you don't need to delete the answer = 0 variable in the global scope

edited Sep 02 '23 at 17:21

answered Sep 02 '23 at 17:20

Frederick

14
1

ooh thanks sooo much @fredrick. this helped SOOO much <3 – A.H Moussa Sep 02 '23 at 17:25
This is really bad practice. Functions should `return` the result, not modify some global variable. – Thierry Lathuille Sep 02 '23 at 18:29

score -1 · Answer 2 · answered Sep 02 '23 at 17:28

main problem is your function is not returning any value. your are trying to print a local variable which is answer. so i change the code a bit so that it works. However, you can optimize the code further: #inputs and stuff VV

num_1 = input("What's Your First Number?:  ")
operation = input(" + \n - \n * \n / \n Pick An Operation:  ")
num_2 = input("What's Your next Number?:  ")


#functions
def addition():
  answer = int(num_1) + int(num_2)
  return answer

def subtraction():
  answer = int(num_1) - int(num_2)
  return answer

def multiplication():
  answer = int(num_1) * int(num_2)
  return answer

def division():
  answer = int(num_1) / int(num_2)
  return answer

def continue_prog():
  print(answer)
  operation = input(" + \n - \n * \n / \n Pick An Operation:  ")
  new_num_2 = input("What's Your next Number?:  ")
  print(f" {answer} {operation} {new_num_2} = {answer}")

def Continue_or_not():
  continue_or_not = input(f"Typer 'Y' to Continue Calculating With {answer}. \n Or Type 'N' To   Begin New Operation \n Or 'C' To Close The Calculator: ")

if continue_or_not == "Y":
continue_prog()

  if continue_or_not == "N":
    clear()
    answer = 0
    num_1 = input("What's Your First Number?:  ")
    operation = input(" + \n - \n * \n / \n Pick An Operation:  ")
    num_2 = input("What's Your next Number?:  ")

  else:
    exit()
  
  
  
  

#computer checking which operation was picked
def chosen_operation():
  if operation == '+':
    return addition()
  if operation == "-":
    return subtraction()
  if operation == "*":
    return multiplication()
  if operation == "/":
    return division()

answer = chosen_operation()


#Actual Code
print(f" {num_1} {operation} {num_2} = {answer}")
continue_or_not = input(f"Typer 'Y' to Continue Calculating With {answer}. \nOr Type 'N' To Begin New Operation \nOr 'C' To Close The Calculator: \n")

if continue_or_not == "Y":
  continue_prog()

else:
  print(f"Result:{answer}")

Thanks so much Shohidul! You helping me has made my day! thanks. God bless you — A.H Moussa, Sep 02 '23 at 17:30

Error in calculator program using python. NameError

2 Answers2