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Local vs Global Variables in Python



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Local vs Global Variables in Python

Understanding the scope of variables is crucial in programming. In Python, variables can be classified as local or global depending on where they are declared and used.

Global Variables

Global variables are defined outside of all functions and can be accessed anywhere in the code.


# This is a global variable
x = 10

def print_global():
    # Accessing global variable inside a function
    print(x)

print_global()  # Output: 10

Local Variables

Local variables are declared inside a function and can only be accessed within that function.


def print_local():
    # This is a local variable
    y = 5
    print(y)

print_local()  # Output: 5

# Trying to access local variable outside its scope will cause an error
print(y)  # NameError: name 'y' is not defined

Global Keyword

The global keyword allows you to modify a global variable inside a function.


z = 20

def modify_global():
    global z
    z = 30

modify_global()
print(z)  # Output: 30

Nonlocal Keyword

The nonlocal keyword allows you to modify a variable in the nearest enclosing scope (excluding global scope).


def outer_function():
    a = 10

    def inner_function():
        nonlocal a
        a = 20

    inner_function()
    print(a)  # Output: 20

outer_function()

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