Why do I get a "referenced before assignment" error when assigning to a global variable in a function?

Question

In Python, I’m getting the following error:

UnboundLocalError: local variable 'total' referenced before assignment

At the start of the file (before the function where the error comes from), I declare total using the global keyword. Then, in the body of the program, before the function that uses total is called, I assign it to 0. I’ve tried setting it to 0 in various places (including the top of the file, just after it is declared), but I can’t get it to work.

Does anyone see what I’m doing wrong?

Asked By: Jeremy

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Source

Answer 1

I think you are using ‘global’ incorrectly. See Python reference. You should declare variable without global and then inside the function when you want to access global variable you declare it global yourvar.

#!/usr/bin/python

total

def checkTotal():
    global total
    total = 0

See this example:

#!/usr/bin/env python

total = 0

def doA():
    # not accessing global total
    total = 10

def doB():
    global total
    total = total + 1

def checkTotal():
    # global total - not required as global is required
    # only for assignment - thanks for comment Greg
    print total

def main():
    doA()
    doB()
    checkTotal()

if __name__ == '__main__':
    main()

Because doA() does not modify the global total the output is 1 not 11.

Answered By: stefanB

Answer 2

My Scenario

def example():
    cl = [0, 1]
    def inner():
        #cl = [1, 2] # access this way will throw `reference before assignment`
        cl[0] = 1 
        cl[1] = 2   # these won't

    inner()

Answered By: zinking

Answer 3

def inside():
   global var
   var = 'info'
inside()
print(var)

>>>'info'

problem ended

Answered By: ninja

Answer 4

I want to mention that you can do like this for the function scope

def main()

  self.x = 0

  def increment():
    self.x += 1
  
  for i in range(5):
     increment()
  
  print(self.x)

Answered By: Gennadiy Ryabkin

Why do I get a "referenced before assignment" error when assigning to a global variable in a function?

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