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Showing content from https://intellipaat.com/blog/how-to-use-a-global-variable-in-a-function-in-python/ below:

How to Use a Global Variable in a Function in Python?

Using a global variable in a function allows you direct access with the global keyword. It can also be passed as an argument to the function. Another option is to store it in structures like dictionaries or objects for easier handling.

Table of Contents: 

• Methods to Use a Global Variable in a Function in Python
  • Method 1: Using the Global Keyword in Python
  • Method 2: Using the globals() Function in Python
  • Method 3: Using a Global Dictionary in Python
  • Method 4: Using Environment Variables (os.environ) in Python
  • Method 5: Using a Class Variable (self.variable) in Python
  • Method 6: Using the Mutable Datatypes (Lists and Tuples) in Python
  • Method 7: Using a Singleton Class in Python
• Conclusion

Python provides various methods to use a global variable in a function in Python. Following are some of these methods explained with examples:

The global keyword allows you to modify a global variable inside a function. 

Example:

Output:

Explanation:

The global keyword is used to modify a global variable inside the function. In the example, the value of x is updated from 10 to 20.

The globals() function allows you to access and modify global variables. It returns a dictionary containing all global names and their values.

Example:

Output:

Explanation:

The global() returns a dictionary containing all global variables. Inside the function, we use global() [“c”] to access the global c, even if local c  is already defined. 

You can store global variables in a dictionary and then access or modify them inside functions. 

Example:

Output:

Explanation:

In the update_global_dict(), we access the dictionary using the global keyword and update the values of ‘a’ and ‘c’. A global dictionary can hold multiple global variables. This method is useful for managing several global variables together.

The environment variables can be used to store and access global data in Python. The os.environ provides access to environment variables.

Example:

Explanation: Environment variables are accessed through os.environ, and here, ‘GLOBAL_VAR’ is defined as 18 to 25.

Global variables can be defined as class variables and then accessed through the class or an instance.

Example:

Output:

Explanation:

Here, the global variable is defined as class variable x, which is modified using a static method by concatenating ” Blogs”, and then printing the ”Intellipaat Blogs”.

The mutable datatypes like lists and tuples help in the modification of the global variables without using the global keyword.

Example:

Output:

Explanation: 

Here the global variable is defined in the form of a list. Lst[0] updates the global variable defined and returns the updated global variable as “Intellipaat is an excellent platform for upskilling.

A singleton function ensures that a global variable is managed within a single instance, maintaining consistency across the program.

Example:

Output:

Explanation:

Here, the implementation of the singleton class ensures that only one instance manages the global variable x. The modify_global()  updates the value of the global variable x and returns 

“Intellipaat provides flexible learning options and ensures practical learning”.

Python global variables can be controlled in several ways, each fulfilling different purposes. The global keyword or globals() gives direct access, and dictionaries and class variables give structured storage. Mutable types permit changes without the global keyword, and singleton classes provide a controlled global state. Understanding these methods helps you effectively use the global variable in a function in Python.

Learn the basics of Python through these resources, which highlight important concepts, syntax, and operators.

Magic Method in Python – Learn about magic methods in Python through clear examples.

Elif in Python – Delve into the use of the elif statement in Python, supported by practical examples.

Break and Continue – Discover how break and continue work in Python, illustrated with helpful examples.

Python Reserved Words – Covers Python reserved words and demonstrates their use with examples.

Python Interactive Mode Chevron – Overview of Python’s interactive mode and chevron prompt with real-world examples.

Python Yield Keyword – Understand the yield keyword in Python and how it functions, supported by sample code.

Python Tuple – Take a closer look at tuples in Python, with explanations and practical examples.

Set Attribute Error – Learn what causes a setattr error in Python and how to handle it, using examples.

2D Array Input – See how to take input for a 2D array in Python through easy-to-follow examples.

Sahil Mattoo, a Senior Software Engineer at Eli Lilly and Company, is an accomplished professional with 14 years of experience in languages such as Java, Python, and JavaScript. Sahil has a strong foundation in system architecture, database management, and API integration. 

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