What are global and nonlocal variables in Python?

Can you explain the difference between global and nonlocal variables in Python?

Sure! Global variables are defined outside of any function and can be accessed anywhere in the code. Nonlocal variables, on the other hand, are used in nested functions and allow you to modify variables from the enclosing scope.

Can you give me an example of each?

Of course! For a global variable, you might have:

x = 10

def my_function():
    print(x)

For a nonlocal variable:

def outer_function():
    y = 5
    
def inner_function():
        nonlocal y
        y += 1
        print(y)
    inner_function()
outer_function()

What happens if I try to modify a global variable inside a function?

If you want to modify a global variable inside a function, you need to use the global keyword. For example:

global x
x = 20