Mathematical Operators and Dictionaries

Question

I am attempting to make a calculator. To accomplish this, I wanted to take a user input (add, subtract, multiply, divide) and assign it a value, in this case a mathematical operator.
It appears that Python doesn't like assigning an operator as a value to a key in a dictionary.

Did I make a mistake? Here is the code:

def operation_user_performes(user_input):
operation_dict = {
"add" : +,
"subtract" : -,
"multiply" : *,
"divide" : /,
}
return (operation_dict[user_input])

Answer 1

Aside from what HonFu said, you could also use the functional versions of the operators. So to get 2 + 3, you could do operator.add(2, 3).
https://docs.python.org/3/library/operator.html

So the code will have
from operator import add, sub, mul, truediv

Then operation_dic = {"add": add, "subtract": sub, "multiply": mul, "divide": truediv}

And to get the result of the calculation, something like operation_user_performs(user_input)(operand1, operand2)

Answer 2

Yeah, you can't do that.

What you can do is write the operators in string format like '+'.

I assume you want to take user input for the operands too? You can tie them to a single string and evaluate it as code, pattern being:

eval('5'+'+'+'7')

You can also put a function name as a value and execute it by dict access... but defining functions for basic arithmetic operations just for this looks like overkill.

Answer 3

Hehe, nice. :)

Answer 4

Function call statement is wrong
return (operation_dict(user_input))

Answer 5

you have to put two spaces between order of operation, like -*- -=space

Answer 6

Es correcto

Answer 7

Add +
Subtract -
Multiply *
Divition /

Answer 8

https://code.sololearn.com/W4Ty57fq5zId/?ref=app