How Can I Modify Global Variables from Within Python Functions?

Modifying Global Variables Within Functions

In Python, a variable defined within a function is normally confined to that function. However, it's possible to modify or access a variable in the global scope from within a function using the global keyword.

Creating or Using a Global Variable Within a Function

To declare a variable as global within a function, use the following syntax:

global variable_name

Place this declaration at the beginning of the function where you need to modify or use the global variable. For example:

globvar = 0

def my_function():
    global globvar
    globvar += 1
    print(globvar)  # Prints the updated value of globvar

Using a Global Variable in Multiple Functions

Once a variable has been declared as global in one function, you can then use or modify it in other functions without redeclaring it. Here's an example:

def function_1():
    global globvar
    globvar += 1

def function_2():
    global globvar
    print(globvar)  # Prints the updated value of globvar

In this case, both functions share the same global variable globvar. By modifying globvar in function_1, its value is also changed for function_2.

Note:

• It's important to use the global keyword only when working with global variables.
• Failing to use global where appropriate can lead to UnboundLocalError or unexpected behavior.
• Python defaults to creating local variables within functions. Using global explicitly indicates that you want to modify or use a variable in the global scope.

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