How to use/access a Global Variable in a function - Python

In Python, variables declared outside of functions are global variables, and they can be accessed inside a function by simply referring to the variable by its name.

a = "Great"

def fun():
  # Accessing the global variable 'a'
  print("Python is " + a)
  
fun()

Python is Great

Explanation:

• Here a is the global variable assigned the value "Great".
• This function fun() concatenates "Python is " with a+ and print "Python is Great".

Defining by using global Keyword:

By default, variables created inside a function are local to that function. To modify or create a global variable inside a function, you can use the global keyword, which allows the function to access and update the global variable.

def fun():
  # declaring varible by global keyword
  global a
  a = "great"
# function calling
fun()
print("Python is " + a)

Python is great

Accessing a Global Variables:

Global Variables can be accessed inside functions by simply referring to their name. As long as the variable is not reassigned inside the function, you can use its value directly.

x = 10

def fun():
    # Using the global keyword to modify the global variable x
    global x
    
    x = 20
# Calling the function to modify the global variable
fun()
print(x)

20

Explanation:

• The global variable x is initially set to 10, and inside the fun() function.
• After calling fun(), the global variable x is updated.

Modifying a Global variable:

While you can access global variables inside functions, modifying them requires using the global keyword. Without it, any assignment to a variable inside a function will create a local variable, which will shadow the global variable.

a = "great"

def fun():
  # declaring variable by global keyword
  
  global a
  # modifying the global variable
  
  a = "Great"
fun()
print("Python is " + a)

Python is Great

Explanation:

• The global keyword inside the fun() function allows the function to modify the global variable
• After calling fun(), the global variable a was updated .