Python Scope Of Variable 5

Example 3:
Changing Global Variable From Inside a Function using global

c = 0 # global variable
def add():
    global c
    c = c + 2 # increment by 2
    print("Inside add():", c)

#function calling
add()
print("In main:", c)

When we run above program, the output will be:

output:
Inside add(): 2
In main: 2

In the above program, we define c as a global keyword inside the add() function.

Then, we increment the variable c by 1, i.e c = c + 2. After that, we call the add()function. Finally, we print global variable c.

As we can see, change also occurred on the global variable outside the function, c = 2.

Example 4 :
Share a global Variable Across Python Modules


Create a config.py file, to store global variables

FileName: config.py

a = 0
b = “empty”

Create a update.py file, to change global variables

FileName: update.py

import config

config.a = 10
config.b = “alphabet”


Create a main.py file, to test changes in value

FileName: main.py

import config
import update

print(config.a)
print(config.b)

#Filename: config.py
a = 0
b = "empty"
#FileName: update.py

import config

config.a = 10
config.b = "alphabet"
#FileName: main.py

import config
import update

print(config.a)
print(config.b)

When we run the main.py file, the output will be

10
alphabet

In the above, we create three files:
config.py,
update.py and
main.py.

* The module config.py stores global variables of a and b.

* In update.py file, we import the config.py module and modify the values of a and b.

* Similarly, in main.py file we import both config.py and update.py module.

* Finally, we print and test the values of global variables whether they are changed or not.

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