What am I doing wrong?

Question

I am trying to make a calculator on python, and if I use the '+' symbol, everything executes perfectly. If I dont, it comes up with the error shown below, although according to my code it should say "Try again."

Error:
Traceback (most recent call last):
File "...\Playground\", line 4, in <module>
if a.index ("+")
ValueError: substring not found

https://code.sololearn.com/c0yoGqbZ5fKx/?ref=app

Answer 1

use this condition
if "+" in a:

Answer 2

From the documentation on str() .index() method.

str.index(sub[, start[, end]])¶

Like find(), but raise ValueError when the substring is not found.

It will raise a ValueError when the substring isn't found. You need to handle this.

Answer 3

сам такой