Answer: You can use a global variable in a function by modifying it with the global keyword and passing it as an argument.
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
Python provides various methods to use a global variable in a function in Python. Following are some of these methods explained with examples:
Method 1: Using the Global Keyword in Python
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.
Method 2: Using the globals() Function in Python
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.
Method 3: Using a Global Dictionary in Python
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.
Method 4: Using Environment Variables (os.environ) in Python
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.
Method 5: Using a Class Variable (self.variable) in Python
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”.
Method 6: Using the Mutable Datatypes (Lists and Tuples) in Python
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.
Method 7: Using a Singleton Class in Python
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”.
Conclusion
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.
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