*args and **kwargs in Python

What Are *args and **kwargs in Python?

In Python, *args and **kwargs allow you to pass a variable number of arguments to a function.

Using *args in Python

Definition:

*args allows a function to accept any number of positional arguments (as a tuple).

Syntax:

def function_name(*args):
    for arg in args:
        print(arg)

Example:

def print_numbers(*args):
    for number in args:
        print(number)

print_numbers(1, 2, 3, 4)

Output:

1
2
3
4

Using **kwargs in Python

Definition:

**kwargs allows a function to accept any number of keyword arguments (as a dictionary).

Syntax:

def function_name(**kwargs):
    for key, value in kwargs.items():
        print(f"{key} = {value}")

Example:

def print_info(**kwargs):
    for key, value in kwargs.items():
        print(f"{key}: {value}")

print_info(name="Alice", age=25, city="New York")

Output:

name: Alice
age: 25
city: New York

Combine *args and **kwargs

You can use both in the same function to handle all kinds of arguments.

Example:

def display_data(*args, **kwargs):
    print("Args:", args)
    print("Kwargs:", kwargs)

display_data(10, 20, name="John", age=30)

Output:

Args: (10, 20)
Kwargs: {'name': 'John', 'age': 30}

Important Rules

• *args must come before **kwargs in the function definition
• The order should be:

  def func(positional, *args, keyword=default, **kwargs):

Real-World Use Case Example

Logging Any Message

def log_message(*args, **kwargs):
    print("Log:", *args)
    if kwargs:
        print("Metadata:")
        for k, v in kwargs.items():
            print(f"{k} = {v}")

log_message("User login", user="admin", status="success")

Output:

Log: User login
Metadata:
user = admin
status = success

When to Use *args and **kwargs