Python - Variable problem

Question

I don’t know where I’m going wrong, but I wrote the following line of code:

#variaveis globais
fcfs = False
#commands

def fcfscheck():

    fcfs = not fcfs

Supposedly this function should alternate the value of fcfs between true and false every time it was called, but I’m getting an error:

Unresolved Reference 'fcfs'

Answer 1

This is a name conflict, you have a local variable with the same name as a variable declared in the global scope, change the name of one of its variables and no more conflict.

And as the local variable takes precedence, soon it will not be possible to obtain the value of fcfs because it does not yet exist in the local scope of its function, however, if I change the name of its local variable there will be no conflict, see:

#variaveis globais
fcfs = False
#commands

def fcfscheck():
  outroNome = not fcfs

And if you want to reference your global variable without changing the name, do what was suggested in the other answers global fcfs, but try to make it easier for those who read your code.

Answer 2

Try this way:

def fcfscheck():
   global fcfs
   fcfs = not fcfs

It is necessary to indicate in the function that you want to modify the global variable.

Answer 3

You need to use the global in the variable to use itself within a function

#variaveis globais
fcfs = False
#commands

def fcfscheck():
    global fcfs
    fcfs = not fcfs

A cool tip, I don’t know which IDE you use, in my case I use Vscode with the Pylint extension, it indicates these errors easily