What Does the Asterisk (*) Do in Python Functions?

What is the Significance of the Asterisk (*) in Python?

The asterisk (*) holds a significant purpose in Python, comparable to its usage in C. In Python, it serves multiple roles in function definitions and calls.

Function Definitions with Asterisk Argument:

In function definitions, the syntax *identifier introduces a parameter that gathers any remaining positional arguments into a tuple. If no excess arguments are provided, it defaults to an empty tuple. The following function definition demonstrates this concept:

def get(*a, **kw)

Here, a collects any extra positional arguments, while kw gathers any excess keyword arguments into a dictionary.

Function Calls with Asterisk Argument:

When calling a function, the asterisk can be employed to unpack arguments stored in tuples or dictionaries. For instance:

Positional Arguments:

def foo(a, b, c, *args):
    print(a, b, c, args)

args_tuple = ("testa", "testb", "testc", "excess")
foo(*args_tuple)  # unpacks positional arguments from a tuple

Keyword Arguments:

def foo(a, b, c, **args):
    print(a, b, c, args)

arg_dict = {"a": "testa", "b": "testb", "c": "testc", "excessarg": "string"}
foo(**arg_dict)  # unpacks keyword arguments from a dictionary

The asterisk operator allows for flexible handling of excess arguments in both function definitions and calls. For an in-depth explanation, refer to the Python Language Reference under "Function Definitions" and "Function Calls."

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