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Ok, so I've been looking around for around 40 minutes for how to set a global variable on Python, and all the results I got were complicated and advanced questions and more so answers. I'm trying to make a slot machine in Python, and I want to make a coins system, where you can actually earn coins so the game is better, but when I ran the code, it told me 'UnboundLocalError: local variable referenced before assignment'. I made my variable global, by putting:
global coins
coins = 50
which for some reason printed '50' and gave the UnboundLocalError error again, so from one answer I tried:
def GlobalCoins():
global coins
coins = 50
which, despite the following error, didn't print '50': 'NameError: global name 'coins' is not defined'. Soo I don't really know how to set one. This is probably extremely basic stuff and this is probably also a duplicate question, but my web searches and attempts in-program have proved fruitless, so I'm in the doldrums for now.
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We declare a variable global by using the keyword global before a variable. All variables have the scope of the block, where they are declared and defined in. They can only be used after the point of their declaration.
If a variable is assigned a new value anywhere within the function's body, it's assumed to be a local. If a variable is ever assigned a new value inside the function, the variable is implicitly local, and you need to explicitly declare it as 'global'.
You can use global to declare a global function from within a class. The problem with doing that is you can not use it with a class scope so might as well declare it outside the class.
A global variable in Python is often declared as the top of the program. In other words, variables that are declared outside of a function are known as global variables. You can access global variables in Python both inside and outside the function.
Omit the 'global' keyword in the declaration of coins outside the function. This article provides a good survey of globals in Python. For example, this code:
def f():
global s
print s
s = "That's clear."
print s
s = "Python is great!"
f()
print s
outputs this:
Python is great!
That's clear.
That's clear.
The 'global' keyword does not create a global variable. It is used to pull in a variable that already exists outside of its scope.
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