Global Scope

A variable, with global scope can be used anywhere in the program. It can be created by defining a variable outside the scope of any function/block.

Rules of global Keyword

The basic rules for global keyword in Python are:

When we define a variable outside 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

Use of global Keyword

Example : Accessing global Variable From Inside a Function

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

Output:

Example : Accessing global Variable From Inside a Function

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

Output:

Example : Modifying Global Variable From Inside the Function

c = 1 # global variable
def add():
	c = c + 2 # increment c by 2
	print(c)
add()

Output:

Unbound Local Error: local variable 'c' referenced before assignment

Example : Changing Global Variable From Inside a Function using global keyword

x = 0 # global variable
def add():
	global x
	x = x + 5 # increment by 2
	print ("Inside add() function x value is :", x)
add()
print ("In main x value is :", x)

Output:

Inside add() function x value is : 5

In main x value is : 5

In the above program, x is defined as a global variable. Inside the add() function, global keyword is used for x and we increment the variable x by 5. Now We can see the change on the global variable x outside the function i.e the value of x is 5.