When do I need to use the global keyword in python

Question

Okay, so I\'ve had this really annoying problem where a variable got set locally but then outside of that function reverted to it\'s old self (in this case None), but at the

Answer 1

If you only need to read the value of a global variable in a function, you don't need the global keyword:

x = 3
def f():
    print x

If you ever set the value of a global variable, you need the keyword so that you don't create a local variable:

x = 3
def f():
    global x
    x = 5

f()
print x