Global Variables in Python

In Python, variables defined outside any function are classified as global variables.

A global variable is accessible from any part of a program.

Conversely, variables declared within a function are local variables and can only be accessed within their respective function.

Take the variable x, for example; it is a global variable because it exists outside any function definitions.

x = "ok"
def func()
print(x)
func()

As such, it can be accessed by the func() function.

The output of this script will be:

ok

If a function defines a local variable with the same name as a global variable, it won't impact the value of the global variable.

x = "yes"
def func()
x = "no"
func()
print(x)

Here, the local variable x = "no" is confined to the function's scope.

The output from the function will be:

yes

To modify a global variable from within a function, it must be explicitly declared as global using the 'global' keyword.

x = "yes"
def func()
global x
x = "no"
func()
print(x)

This change will cause the function to replace the global variable’s value.

In this scenario, the function's output is:

no

It's also possible to create a new global variable within a function by declaring it global.

def func()
global y
y = "yes"
func()
print(y)

Consequently, the output from the function is:

yes