Calculate a Python string

Question

I would like to make a calculation of a string that I receive, for example:

var = '1+2'

Wanted to turn this string into an account, to return 3 to the variable var and not '1+2', but this would not only be added, it would have subtraction, multiplication and division, it could still have a mixed operation, ex: var = '2*4+1' and so on... I think you’ve understood...

The problem is that I get this account as string

I tried to use the int(var), but it certainly wouldn’t have some function like calc(var)?

Answer 1

Assuming you will be careful with the inputs you receive the simplest way is:

var = '1+2'
print(eval(var)) # 3

var = '5*3'
print(eval(var)) # 15

As @jsbueno said well, you can use Ast.literal_eval, which is safer if you don’t have control over the inputs that enter the function eval():

import ast
print(ast.literal_eval('4+10')) # 14