How Do I Declare and Use Global Variables within Python Functions?

Declaring and Using Global Variables within Functions

In Python, creating or using a global variable inside a function can be achieved through the global keyword.

Declaring a Global Variable

To create or use a global variable within a function, you must declare it as global before assigning a value to it. For example:

globvar = 0

def set_globvar_to_one():
    global globvar
    globvar = 1

Accessing a Global Variable

Once a global variable has been declared, it can be accessed within other functions without using the global keyword. For example:

def print_globvar():
    print(globvar)

Pitfalls and Considerations

It's important to note that Python defaults to creating local variables when assigning values within functions. Therefore, it's essential to explicitly declare a global variable as such if you intend to modify its value within a function. If you fail to use the global keyword, you may encounter an UnboundLocalError.

Additionally, it's worth mentioning that while this method effectively allows you to share a variable across different functions within a single module, sharing global variables across modules is not recommended in Python. For module-wide variable sharing, it's preferable to use a different approach, such as importing the variable from another module.

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