Using and Accessing Global Variables in Python Functions

General Discussions
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#1

How do I use Python global variables inside a function?

How can I create or access a global variable within a function in Python?

How can I use a global variable that was defined in one function inside other functions in Python?

#2

Ah, this is a pretty common situation in Python programming. To use a Python global variable inside a function, you’ll need the global keyword. It signals to Python that you’re not creating a new local variable but are referring to the global one. Here’s a quick example:

x = 10  # Global variable

def modify_variable():
    global x  # Referencing the global variable
    x = 20  # Modifies the global variable

modify_variable()
print(x)  # Output will be 20

By declaring x as global, any changes made inside the function reflect on the global x.

#3

Building on what Priyanka explained, there’s also a case where you want to use a Python global variable but not modify it. In that case, you don’t even need the global keyword. Simply access the variable directly. Here’s how:

x = 10  # Global variable

def read_variable():
    print(x)  # Accesses the global variable without changing it

read_variable()  # Output will be 10

This way, you’re just reading the value of the global variable without altering it. Clean and simple!

#4

Great points by Priyanka and Ishrath! Let me add to this by showing how Python global variables work across multiple functions. If you’re just accessing the global variable, you don’t need global. But, if one function modifies it, you’ll need global there. Let’s see this in action:

x = 10  # Global variable

def function1():
    global x
    x = 15  # Modifies the global variable

def function2():
    print(x)  # Accesses the global variable

function1()
function2()  # Output will be 15

So, you can easily share a global variable between functions, just remember the rule: Use global only when you’re modifying it.