Python: Flags which are inputted into functions from other functions

Question

I'm trying to create a basic calculator and have a small problem I cant quite get. When you press the number buttons the input box will add the numbers until you then press a math key where the numbers will reset. What I cant work out is, say you put a number in like 8 then hit the inverse key, the output will show 0.125, then when you start typing again it will delete all things in the output window. Here is what I have but isn't working.

def button_click(number):
    if Flag == True:
        e.delete(0,END)
        e.insert(0, str(number))
    else:
        Current = e.get()
        e.delete(0,END)
        e.insert(0, str(Current) + str(number))
    global Flag
    Flag = False

and for the inv function

def button_inv():
    Current = float(e.get())
    e.delete(0, END)
    e.insert(0, 1/Current)
    global Flag
    Flag = True

Anyone have any ideas? Thanks.

I will get the error UnboundLocalError: local variable 'Flag' referenced before assignment — Levy77
– Levy77, Commented Jul 19, 2020 at 6:23
Hi! Usually when getting exceptions, it is helpful to post the full stack-trace as well. That helps to know on which line the exception happened. Could you add it to your question please? — unddoch
– unddoch, Commented Jul 19, 2020 at 6:26
Also, I think the problem is you need to put "global Flag" at the start of your function. — unddoch
– unddoch, Commented Jul 19, 2020 at 6:27

Roshin Raphel · Accepted Answer · 2020-07-19 08:29:52Z

1

Your placement of the global Flag is wrong, it should be placed at the beginning.

def button_click(number):
    global Flag
    if Flag == True:
        e.delete(0,END)
        e.insert(0, str(number))
    else:
        Current = e.get()
        e.delete(0,END)
        e.insert(0, str(Current) + str(number))
    Flag = False

and

def button_inv():
    global Flag
    Current = float(e.get())
    e.delete(0, END)
    e.insert(0, 1/Current)
    Flag = True

and declare Flag = False at the beginning of your code.

answered Jul 19, 2020 at 8:29

Roshin Raphel

2,7195 gold badges28 silver badges43 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Python: Flags which are inputted into functions from other functions

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related