What Are Local And Global Variables In Python By Gagan Khanna

1. Local Variables

A Local variable is defined inside a function. Its existence is confined to that function's "block." Once the function finishes executing, the local variable is destroyed, and its data is no longer accessible.

Example:

def greet():
    message = "Hello, Local Scope!"  # This is a local variable
    print(message)

greet()
# print(message)  # This would raise a NameError

• Scope: Limited to the function greet().

• Accessibility: Cannot be accessed from outside the function.

2. Global Variables

A Global variable is defined outside of any function, usually at the top level of the script. These variables are accessible from anywhere in the code—both inside and outside of functions.

Example:

total_score = 100  # This is a global variable

def show_score():
    print(f"Your current score is: {total_score}")

show_score()
print(f"Global access: {total_score}")

• Scope: The entire program.

• Accessibility: Accessible by any function in the file.

3. The global Keyword

By default, if you try to modify a global variable inside a function, Python treats it as creating a new local variable with the same name. To modify the actual global variable, you must use the global keyword.

Example:

count = 0

def increment():
    global count  # Tells Python to use the global 'count'
    count += 1
    print(f"Inside function: {count}")

increment()
print(f"Outside function: {count}")

4. Key Differences at a Glance