What are the rules for local and global variables in Python?

Scope of Variables in Python are of two types: local and global. Scope is defined as the accessibility of a variable in a region. Let us first understand both local and global scope before moving towards the rules.

Local Scope

Example

This defines the local scope of a variable i.e. it can be accessed only in the function where it is defined. No access for a variable with local scope outside the function. Let’s see an example −

# Variable with local scope can only be access inside the function
def example():
   i = 5
   print(i)

# An error is thrown if the variabke with local scope
# is accessed outside the function
# print(i)
# Calling the example() function
example()

Output

5

Global Scope

Example

If a variable is accessible from anywhere i.e. inside and even outside the function, it is called a Global Scope. Let’s see an example −

# Variable
i = 10

# Function
def example():
   print(i)

print(i) # The same variable accessible outside the function

# Calling the example() function
example()
# The same variable accessible outside
print(i)

Output

10
10
10

Rules for local and global variable

Following are the rules −

• Variables that are only referenced inside a function are implicitly global.

• If a variable is assigned a value anywhere within the function’s body, it’s assumed to be a local unless explicitly declared as global.

• Variable with a local scope can be accessed only in the function where it is defined.

• Variable with Global Scope can be accessed inside and outside the function.