Scope in Python

In Python, Scope determines where a variable is accessible within a program. In simple words, scope tells us where a variable can be used.

1. What is Scope?

Scope means the variable's visibility and accessibility.

In Python, beginners should mainly understand two important scopes:

• Local Scope
• Global Scope

2. Local Scope

A variable created inside a function is generally a local variable. It can be accessed inside the function.

def greet():

    message = "Hello CIIT"

    print(message)


greet()

Output:

Hello CIIT

Here, message is created inside the function, so its scope is limited to the function.

3. Local Variable Outside Function

Trying to access a local variable directly outside the function will result in an error.

def greet():

    message = "Hello CIIT"

    print(message)


greet()

print(message)

4. Global Scope

A variable created outside a function is a global variable.

course = "Python Full Stack"


def show_course():

    print(course)


show_course()

print(course)

Output:

Python Full Stack
Python Full Stack

A global variable can also be accessed inside a function.

5. Local Scope vs Global Scope

6. Same Variable Name in Different Scopes

The same variable name can exist in local and global scopes.

course = "Python"


def show_course():

    course = "Java"

    print("Inside:", course)


show_course()

print("Outside:", course)

Output:

Inside: Java
Outside: Python

The local course is used inside the function, while the global course is used outside the function.

7. global Keyword

If you want to modify a global variable inside a function, you can use the global keyword.

count = 10


def update_count():

    global count

    count = 20


update_count()

print(count)

Output:

20

8. Why global is Needed?

When an assignment is made inside a function, Python normally treats that variable as a local variable.

count = 10


def update_count():

    count = 20

    print("Inside:", count)


update_count()

print("Outside:", count)

Output:

Inside: 20
Outside: 10

Here, a new local variable was created inside the function. The global variable was not changed.

9. Global Variable Example 🤓❤️

institute = "CIIT Training Institute 🤓👀...!"


def display_institute():

    print(institute)


display_institute()

Output:

CIIT Training Institute 🤓👀...!

10. Function Parameters and Scope

Function parameters also behave like local variables inside the function.

def greet(name):

    print("Hello", name)


greet("Amit")

Output

Hello Amit

Here, name is a parameter and is available in the function's local scope.

11. Nested Function Scope

In Python, one function can be defined inside another function.

def outer():

    message = "Hello from Outer"

    def inner():

        print(message)

    inner()


outer()

Output:

Hello from Outer

The inner function can access the outer function's variable.

12. Enclosing Scope

In nested functions, the outer function's scope is called the enclosing scope.

def outer():

    name = "CIIT"

    def inner():

        print(name)

    inner()


outer()

Output:

CIIT

13. LEGB Rule

When searching for a variable, Python follows the LEGB Rule.

14. Built-in Scope

Python's built-in functions and objects are available in the built-in scope.

numbers = [10, 20, 30]

print(len(numbers))

print(max(numbers))

print(sum(numbers))

Output:

3
30
60

15. CIIT Example 👀🤓

Suppose the institute name is global in a CIIT application, and the student name is local inside the function.

institute = "CIIT Training Institute ❤️😍...!"


def student_details(name):

    course = "Python Full Stack"

    print("Institute:", institute)
    print("Student:", name)
    print("Course:", course)


student_details("Rahul")

Output:

Institute: CIIT Training Institute ❤️😍...!
Student: Rahul
Course: Python Full Stack

16. Scope Best Practices

• Keep variables limited to the scope where they are required.
• Avoid unnecessary global variables.
• Use parameters for function inputs.
• Use return to get a result from a function.
• Use meaningful variable names.

17. Common Mistakes

def student():

    name = "Amit"


student()

print(name)

Here, name is a local variable. Therefore, it cannot be accessed outside the function.

18. Interview Points

• What is scope in Python?
• What is the difference between local and global variables?
• When is the global keyword used?
• What is the LEGB rule?
• What is the scope of a function parameter?
• Can an inner function access a variable from the outer function?