"Local variable referenced before assignment" error

Question

I get "local variable 'answer' referenced before assignment" error with my code. How should I resolve this?

from Tkinter import *
import Tkinter


def proces():

  F=Entry.get(E1)
  m=Entry.get(E2)
  a=Entry.get(E3)
  if F ==0:
      answer=float(m)*float(a)
  if m ==0:       
      answer=float(F)/float(a)
  if a ==0:
      answer=float(F)/float(m)
  Entry.insert(E4,0,answer)
  print(answer)

#And the rest of the GUI coding goes here. 

top = Tkinter.Tk()
L1 = Label(top, text="My calculator",).grid(row=0,column=1)
L2 = Label(top, text="Force",).grid(row=1,column=0)
L3 = Label(top, text="Weight",).grid(row=2,column=0)
L4 = Label(top, text="Accelaration",).grid(row=3,column=0)
L4 = Label(top, text="Solution",).grid(row=4,column=0)
E1 = Entry(top, bd =5)
E1.grid(row=1,column=1)
E2 = Entry(top, bd =5)
E2.grid(row=2,column=1)
E3 = Entry(top, bd =5)
E3.grid(row=3,column=1)
E4 = Entry(top, bd =5)
E4.grid(row=4,column=1)
B=Button(top, text ="Solve",command = proces).grid(row=5,column=1,)

top.mainloop()

just define `answer=0 or some vale` above `IF`, just think about if none of the condition satisfies what will be the value for answer ? — Vikas Periyadath, Feb 06 '18 at 06:54
Welcome to [so]! Please provide a [mcve] for the question you're asking as opposed to your current code. — Nae, Feb 06 '18 at 11:01

score 0 · Answer 1 · edited Feb 06 '18 at 11:11

0

Give like this :

answer = "the value which you can give as default"
if F ==0:
  answer=float(m)*float(a)
if m ==0:       
  answer=float(F)/float(a)
if a ==0:
  answer=float(F)/float(m)

or

if F ==0:
  answer=float(m)*float(a)
elif m ==0:       
  answer=float(F)/float(a)
elif a ==0:
  answer=float(F)/float(m)
else :
  answer = "the value which you can give as default"

If none of the conditions is matching which value you want to assign to answer? that value you can give in mentioned place in that above answers

edited Feb 06 '18 at 11:11

Nae

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answered Feb 06 '18 at 06:57

Vikas Periyadath

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Nope it gives the answer as '0' – cee Feb 06 '18 at 07:01
what are your other values ? Try to print answer in in each if and check it – Vikas Periyadath Feb 06 '18 at 07:03
tried printing answer after each if . Then nothing happens after I enter 2 numbers in 2 of 3 fields and press solve.Any help"? – cee Feb 06 '18 at 07:15
I can help you but need to know what values you are passing to F,m and a ? – Vikas Periyadath Feb 06 '18 at 07:17
I don`t know exactly wt you meant. But I`m entering floating point numbers(or integers). – cee Feb 06 '18 at 07:20
try print `F ,m and a`, then just mention here. – Vikas Periyadath Feb 06 '18 at 07:22
I got what you said . When I do this it prints 0 as answer. On a side note can you please tell me whether I have written "Entry.insert(E4,0,answer)" corectly? – cee Feb 06 '18 at 07:29
1

This _is_ the answer. – Nae Feb 06 '18 at 11:11

score 0 · Answer 2 · answered Feb 06 '18 at 06:58

0

You are assigning value to variable 'answer' inside the if statement so its scope is limited to those if statements, simply initialize your variable answer before if statement.

answered Feb 06 '18 at 06:58

Usama Wajhi

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1
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Can you please show me how to do this? , Cus when I assign 'answer=0' before is statements the solution(answer) prints out as 0 allways. – cee Feb 06 '18 at 07:13
After initializing answer=0 If you are getting '0' as your answer at the end, this means none of the if conditions are being executed, so you've to check the values you are passing to F, m, a. – Usama Wajhi Feb 07 '18 at 06:26

score 0 · Answer 3 · answered Feb 06 '18 at 08:05

0

Thank You very much for your quick replies.

I finally solved it .

All I had to do is make if (variable)==0: to if len(variable)==0:

I hope anyone who get this problem in the future will find this helpful.

answered Feb 06 '18 at 08:05

cee

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2

"Local variable referenced before assignment" error

3 Answers3