Python에서 전역 변수를 사용하는 방법(전역 키워드)

counter = 10 # Global variable

def read_counter():
    # Reading a global variable works out-of-the-box
    print("Reading global counter:", counter)

def shadow_counter():
    # Attempting to assign without 'global' creates a local variable
    counter = 20 # Shadowing
    print("Inside shadow function:", counter)

def modify_counter():
    global counter # Declaring we are writing to global scope
    counter = 50
    print("Inside modify function:", counter)

read_counter()
shadow_counter()
print("Counter after shadow function:", counter) # Remains 10

modify_counter()
print("Counter after modify function:", counter) # Now 50

Reading global counter: 10
Inside shadow function: 20
Counter after shadow function: 10
Inside modify function: 50
Counter after modify function: 50