Python Scope Of Variable 4

Introduction to global Keyword

In Python, global keyword allows you to modify the variable outside of the current scope. It is used to create a global variable and make changes to the variable in a local context.

Rules of global Keyword

The basic rules for global keyword in Python are:

• When we create a variable inside a function, it’s local by default.

• When we define a variable outside of a function, it’s global by default. You don’t have to use global keyword.

• We use global keyword to read and write a global variable inside a function.

• Use of global keyword outside a function has no effect

Example 1:
Accessing global Variable From Inside a Function

c=1 # global variable
def sample():
    print(c)

#function calling
sample()

When we run above program, the output will be:

1

However, we may have some scenarios where we need to modify the global variable from inside a function.

Example 2:
Modifying Global Variable From Inside the Function

c=1 # global variable
def sample():
    c=c+100
    print(c)

#function calling
sample()

When we run above program, the output shows an error:

UnboundLocalError: local variable ‘c’ referenced before assignment

This is because we can only access the global variable but cannot modify it from inside the function.

The solution for this is to use the global keyword.

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