use global variable in function, python

use global variable in function, python

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Using Global Variables in Python Functions

In Python, global variables are variables that are defined outside of any function or method and can be accessed from anywhere within the program. When you want to use a global variable inside a function, you don't need to pass it as an argument like you would with local variables.

Let's explore this concept with some examples!

Example 1: Accessing a Global Variable

Suppose we have a global variable greeting defined outside of any function or method:

greeting = "Hello, World!"

Now, let's define a function print_greeting() that tries to access this global variable:

def print_greeting():
print(greeting)
print_greeting()  # Output: Hello, World!

As you can see, the function print_greeting() is able to access the global variable greeting without passing it as an argument.

Example 2: Modifying a Global Variable

Let's modify the previous example by changing the value of the global variable inside the function:

greeting = "Hello, World!"
def print_greeting():
print(greeting)
greeting = "Goodbye, World!"
print(greeting)
print_greeting()  # Output:
Hello, World!
Goodbye, World!

In this example, we modify the value of greeting inside the function. The global variable is updated when the function executes.

Important Note:

When a function modifies a global variable, it can cause unintended side effects in other parts of your program! To avoid this, consider using local variables or passing data as arguments instead of relying on global state.

Best Practices:

To use global variables effectively and avoid potential issues:

In conclusion, using global variables in Python can be useful for accessing shared state, but it's essential to understand their implications and use them judiciously!

Hope this helps!

Global variable in python w3schools

Here's an explanation of global variables in Python using W3Schools:

In Python, a global variable is a variable that is defined outside of any function or method. This means that the variable can be accessed from anywhere in the program, including within functions and methods.

To define a global variable in Python, you simply declare it outside of any function or method. For example:

x = 5

This declares a global variable called x with an initial value of 5.

Once declared, the global variable can be accessed from anywhere in the program. For example:

print(x)  # prints 5

In this example, we access the global variable x and print its value.

Note that when you assign a new value to a global variable within a function or method, it only changes the local copy of the variable. The original global variable remains unchanged:

def modify_x():
x = 10
modify_x()
print(x)  # still prints 5

If you want to modify the original global variable from within a function or method, you need to use the global keyword:

x = 5
def modify_x():
global x
x = 10
modify_x()
print(x)  # now prints 10

Here, we declare that x is a global variable using the global keyword. When we assign a new value to x within the function, it changes the original global variable.

Global variables can be useful for storing data that needs to be accessed from multiple parts of your program. However, they can also lead to confusion and bugs if not used carefully. It's generally a good idea to use them sparingly and with caution.

Here are some best practices for using global variables:

I hope this helps! Let me know if you have any questions.