Global and Local Variables in Python?

In Python, variables have different scopes that determine where they can be accessed. There are two main types: global variables (accessible throughout the entire program) and local variables (accessible only within the function where they are defined).

Local Variables

Local variables are created inside a function and can only be accessed within that function. They exist only during the function's execution ?

def my_function():
    x = "Python"  # Local variable
    print("Inside function:", x)

my_function()
# print(x)  # This would cause NameError

Inside function: Python

If you try to access a local variable outside its function, Python raises a NameError.

Global Variables

Global variables are defined outside functions and can be accessed from anywhere in the program ?

message = "Hello World"  # Global variable

def display_message():
    print("Inside function:", message)

display_message()
print("Outside function:", message)

Inside function: Hello World
Outside function: Hello World

Modifying Global Variables

To modify a global variable inside a function, use the global keyword ?

counter = 10  # Global variable

def increment():
    global counter
    counter += 5
    print("Inside function:", counter)

increment()
print("Outside function:", counter)

Inside function: 15
Outside function: 15

Local vs Global Variables Example

When both local and global variables have the same name, the local variable takes precedence inside the function ?

name = "Global"  # Global variable

def test_scope():
    name = "Local"  # Local variable
    print("Inside function:", name)

test_scope()
print("Outside function:", name)

Inside function: Local
Outside function: Global

Comparison

Conclusion

Local variables provide encapsulation and are preferred for function-specific data. Global variables should be used sparingly and with the global keyword when modification is needed inside functions.