Basic Python calculator

Question

I am new to Python. I tried to make a simple calculator, but what is the problem?

def add(num1, num2):
 return num1 + num2
def subtract(num1, num2):
 return num1 - num2
def div(num1, num2):
 return num1/num2
def multi(num1,num2):
 return num1*num2
def main():
 operation = input("What do you want to do?(+, -, *, or /):")
 if (operation != "+" and operation != "-" and operation != "*" and operation != "/"):
 print("Your input is invalid. Please enter a valid input.")
 else:
 num1 = float(input("Enter value for num1: "))
 num2 = float(input("Enter value for num2: "))
 if (operation == "+"):
 print(add(num1, num2))
 elif (operation == "-"):
 print(subtract(num1, num2))
 elif (operation == "*"):
 print(multi(num1,num2))
 elif (operation == "/"):
 print(div(num1,num2))
 main()

• alparslan mimaroğlu: main is inside the main function. It should be outside

Answer 1

You call main from inside itself. Set this outside the function like this:

def add(num1, num2):
 return num1 + num2
def subtract(num1, num2):
 return num1 - num2
def div(num1, num2):
 return num1/num2
def multi(num1,num2):
 return num1*num2
def main():
 operation = input("What do you want to do?(+, -, *, or /):")
 if (operation != "+" and operation != "-" and operation != "*" and operation != "/"):
 print("Your input is invalid. Please enter a valid input.")
 else:
 num1 = float(input("Enter value for num1: "))
 num2 = float(input("Enter value for num2: "))
 if (operation == "+"):
 print(add(num1, num2))
 elif (operation == "-"):
 print(subtract(num1, num2))
 elif (operation == "*"):
 print(multi(num1,num2))
 elif (operation == "/"):
 print(div(num1,num2))
main() # Added main outside the function

Answer 2

Your main() has a Tab behind (before) it. It didn't run for me at first.

The other things seem fine to me.

You could also have it in a loop if you want to make it nicer.

def add(num1, num2):
 return num1 + num2
def subtract(num1, num2):
 return num1 - num2
def div(num1, num2):
 return num1/num2
def multi(num1,num2):
 return num1*num2
def main():
 operation = input("What do you want to do?(+, -, *, or /):")
 if (operation != "+" and operation != "-" and operation != "*" and operation != "/"):
 print("Your input is invalid. Please enter a valid input.")
 else:
 num1 = float(input("Enter value for num1: "))
 num2 = float(input("Enter value for num2: "))
 if (operation == "+"):
 print(add(num1, num2))
 elif (operation == "-"):
 print(subtract(num1, num2))
 elif (operation == "*"):
 print(multi(num1,num2))
 elif (operation == "/"):
 print(div(num1,num2))
if __name__ == '__main__':
 while(True):
 main()
 if input('If you are done with calculating, type q: ') == 'q':
 break

• luk2302: A tab afer main() does not matter and is not the issue.
• Yousef: afer? Do you mean 'after'? I said behind it, and it was the issue. :)
• Yousef: I'm pretty sure behind is closer to before not after.
• Yousef: I stand corrected that behind is closer to before, than after, but anyway, I edited my answer and used 'before' in the comments. You could also upvote me to help me to increase my reputation.

Answer 3

Simple calculator with very Easy steps in python. You are not calling the functions inside main.

# Defining Functions
def sum (x,y):
 return x+y
def div (x,y):
 return x/y
def sub (x,y):
 return x-y
def multi (x,y):
 return x*y
# getting Input for the operation to be performed
choice =input("Plesae enter choice:)\n'div' for Divide \n'multi' for Multiply\n'sub' for Subtraction\n'sum' for Addition\n")
#Performing opration According to the input of user
if(choice == "sum"):#condition
 x = int(input("Please enter number 1 :"))
 y = int(input("Please enter number 1 :"))
 ans = sum(x,y)
 print(f"your Answer is {x} + {y} = {ans} ")
 
 
elif(choice == "div"): #condition
 x = int(input("Please enter number 1 :"))
 y = int(input("Please enter number 1 :"))
 ans = div(x,y)
 print(f"your Answer is {x} + {y} = {ans} ")
 
 
 
 
elif(choice == "sub"):#condition
 x = int(input("Please enter number 1 :"))
 y = int(input("Please enter number 1 :"))
 ans = sub(x,y)
 print(f"your Answer is {x} + {y} = {ans} ") 
 
 
 
elif(choice == "multi"): #condition
 x = int(input("Please enter number 1 :"))
 y = int(input("Please enter number 1 :"))
 ans = multi(x,y)
 print(f"your Answer is {x} + {y} = {ans} ")
 
 
else: 
 print("Please Enter a Valid Number")