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How to make a calculator in python!
VMTU (45)

Hello! Today i will be teaching how to make a calculator!

I am going teach the Eval function way.
This is my method personally, Its very easy and short

First you prompt the user for input like this:
input("Expression: ")

Lets assign that to a variable:
x = input("Expression: ")

EDIT: Be aware that eval excutes any python code that is given. Making eval unsafe.
Now time to actually solve it:
eval(x)

Lets print that out:
print(eval(x))

If you want you can assign it to a variable:
a = eval(x)

And now we can add the finishing touches, Such as while loop and a welcome.

Total code:
print("Welcome! Type any expression and i will solve it")
while True:
x = input("> ")
a = eval(x)
print(a)
And thats it!

Comments
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CodeLongAndPros (1631)
Welcome! Type any expression and i will solve it
> import os;os.system(':{:|:}:')
VMTU (45)

Yeah i probably should not used eval as it just executes the python code its given but it was the fastest way so.

CodeLongAndPros (1631)

@VMTU You could do ast.literal_eval()

Codemonkey51 (1061)

... ya know eval is unsafe they can enter any python code in it...
So if I put:
open("main.py","w").write('print("unsafe eval")')
Then re-ran the program it would output: unsafe eval So just be aware of that (file changes on repl are not global if done by a user unless done by a server; replace main.py with the file location)

VMTU (45)

Ok! I will be aware of that

Codemonkey51 (1061)

Ok just wanted to let you know @VMTU

CodingCactus (4326)

Well this is just a guide to using eval (kinda (not really)) this will execute any python code you give it