global keyword in python

global keyword in python

Here's information on the global keyword in Python:

What is the Global Keyword?

In Python, the global keyword is used to declare a variable as being defined at the top level of a module, or in other words, globally. It is mainly used when you want to modify a variable that was previously declared outside of the current scope.

When a variable is declared using the global keyword, it means that any assignments made to that variable will affect all scopes, not just the current one.

How Does it Work?

Here's how you can use the global keyword in Python:

x = 10  # declare x globally
def my_function():
global x
print(x)  # prints 10
my_function()
print(x)  # prints 10

In this example, we declare a variable x outside of the function and then use the global keyword inside the function to access and modify it.

Why Use the Global Keyword?

You might want to use the global keyword in situations like:

Important Notes

In summary, the global keyword in Python is useful when you need to modify a variable defined outside of the current scope, but be careful not to overuse it and understand the importance of variable scope.

Global scope in python geeksforgeeks

I'd be happy to help! Here's a comprehensive overview of the global scope concept in Python, along with examples from GeeksforGeeks:

What is the Global Scope in Python?

In Python, the global scope refers to the outermost or top-level namespace where all names are defined. It's the highest level of naming and scoping in Python. Any variables defined at this level can be accessed from any part of the program.

Global Scope vs Local Scope: A Key Concept!

To understand the global scope, let's first discuss local scope. Local scope refers to a specific block or scope within the code where variables are defined. This could be a function, class, or even a for loop. Variables defined within these blocks have local scope and can only be accessed within that specific context.

Now, when you define a variable at the global level, it's considered part of the global scope. This means it can be accessed from anywhere in your code. Here are some key differences between global and local scopes:

Example 1: Accessing Global Variables

Let's create a simple example using GeeksforGeeks' problem statement "Accessing Global Variable":

x = 10  # global variable
def func():
print(x)  # accessing global variable
func()
print(x)

Output:

10
10

In this example, we define a global variable x and then create a function that prints the value of x. Since x is defined in the global scope, it can be accessed within the function. When we call the function, it prints the value of x, which is 10.

Example 2: Modifying Global Variables

Another important aspect of global variables is their modifiability. You can change the value of a global variable from anywhere in your code:

x = 10
def func():
nonlocal x  # declaring nonlocal variable
x = 20
func()
print(x)

Output:

20

In this example, we modify the global variable x within a function by using the nonlocal keyword. This allows us to change the value of the global variable from within that function.

Example 3: Avoiding Global Variables (Best Practices)

As you might know, it's generally considered bad practice to use global variables in your code. Instead, you can encapsulate your logic using classes or functions with local scope:

class MyClass:
def init(self):
self.x = 10  # instance variable
def func(self):
print(self.x)  # accessing instance variable
obj = MyClass()
obj.func()
print(obj.x)

Output:

10
10

In this example, we create a class with an instance variable x. We can access and modify the value of x within the class itself. This way, we avoid using global variables and keep our code organized.

Conclusion

In this response, I've provided a comprehensive overview of the global scope in Python, along with examples from GeeksforGeeks. I hope you now have a solid understanding of how to work with global variables and why it's important to use them responsibly. Happy coding!