Python: Unexpected identifier when calling method of class

Question

I would like to write a class Calculator including:

• a function called add that takes two parameters containing double values and returns their sum
• a function called subtract that takes two parameters containing double values and returns their difference (subtract the second from the first)
• a function called multiply that takes two parameters containing double values and returns their product
• a function called divide that takes two parameters containing double values and returns the value of the first divided by the second. If the second number is a zero, do not divide, and return "You can't divide by zero!"

This is my attempt, but apparently it's not correct.

class Calculator: 
    def add(x,y): 
        return x+ y 
    def subtract(x,y): 
        return x - y 
    def multiply(x,y): 
        return x * y 
    def divide(x,y): 
        if y==0: 
            return "You can t divide by zero!" 
        else: 
            return x/y 

From the results, I get unexpected identifier x and y.

Answer 1

Object methods in python need to explicitly define the 'this' parameter you know from 'C', or the argument referring to the object itself. In Python it is usually called 'self'. For example:

class Calc:
    def add(self,x,y): return x+y

Since all your methods do not really need self, and the calculator is more of a container of methods, you can define them as class methods, so Calc.add(3,4) works without creating an object:

class Calc:
    @staticmethod
    def add(x,y): return x+y

If you're new to python please note indentation is very important as well.

Answer 2

This answer will be accepted by the programming lab system:

class Calculator:

   def add(self, x, y):
       self.x = x
       self.y = y
       a = self.x + self.y
       return a
    
   def subtract(self, x, y):
       self.x = x
       self.y = y
       a = self.x - self.y
       return a
    

   def multiply(self, x, y):
       self.x = x
       self.y = y
       a = self.x * self.y
       return a
    

   def divide(self, x, y):      
       self.x = x
       self.y = y
        
       if (y == 0):
           a = "You can't divide by zero!"
       else:
           a = self.x / self.y  
    
       return a

There are more simple soutions but this will be accepted by the programming lab editor. It can be a bit picky at times.

Answer 3

class Calculator:


   def add(self,num1,num2):
    print(num1+num2)

 
 def subtract(self,num1,num2):
    print(num1-num2)
    
 
 def multiply(self,num1,num2):
    print(num1*num2)


 def divide(self,num1,num2):
    print(num1 / num2)



object1 = Calculator()
object2 = Calculator()
object3 = Calculator()
object4 = Calculator()

object1.add(100,200)
object2.subtract(50,30)
object3.multiply(10,3)
object4.divide(250,5)