Function arguments in Python define how data is passed to functions. Python supports several types of arguments:

1. Positional Arguments

These are the most common type. Arguments are matched by position.

def greet(name, age):
   print(f"Hello {name}, you are {age} years old.")
greet("Alice", 25)

Output:

Hello Alice, you are 25 years old.

2. Keyword Arguments

Arguments can also be passed using name=value syntax, regardless of their order.

def greet(name, age):
   print(f"Hello {name}, you are {age} years old.")
greet(age=25, name="Alice")

Output:

Hello Alice, you are 25 years old.

3. Default Arguments

Provide default values for parameters so they become optional.

def greet(name="Guest"):
   print(f"Hello {name}")
greet()           # Uses default
greet("Alice")    # Overrides default

Output:

Hello Guest
Hello Alice

4. Arbitrary Positional Arguments (*args)

Used when you want to allow any number of positional arguments. These are received as a tuple.

def add_numbers(*args):
   total = sum(args)
   print("Sum:", total)
add_numbers(1, 2, 3)
add_numbers(5, 10)

Output:

Sum: 6
Sum: 15

5. Arbitrary Keyword Arguments (**kwargs)

Used to handle any number of keyword arguments. These are received as a dictionary.

def display_info(**kwargs):
   for key, value in kwargs.items():
       print(f"{key}: {value}")
display_info(name="Alice", age=25)

Output:

name: Alice
age: 25

Combining Different Argument Types

Order of arguments must be:

def func(positional, /, positional_or_keyword, *, keyword_only)

Typical combination:

def example(a, b=2, *args, **kwargs):
   print("a:", a)
   print("b:", b)
   print("args:", args)
   print("kwargs:", kwargs)
example(1, 3, 4, 5, x=10, y=20)

Output:

a: 1
b: 3
args: (4, 5)
kwargs: {'x': 10, 'y': 20}

Special Types (Python 3.8+)

1. Positional-Only Parameters (/)

def add(x, y, /):
   return x + y
print(add(2, 3))     # OK
# print(add(x=2, y=3))  # Error!

2. Keyword-Only Parameters (*)

def greet(*, name):
   print("Hello", name)
greet(name="Alice")  # OK
# greet("Alice")     # Error!

Summary Table

Practice Task

def user_info(name, age=18, *skills, **extra):
   print("Name:", name)
   print("Age:", age)
   print("Skills:", skills)
   print("Extra Info:", extra)
user_info("Tom", 20, "Python", "Django", city="Delhi", married=False)

Output:

Name: Tom
Age: 20
Skills: ('Python', 'Django')
Extra Info: {'city': 'Delhi', 'married': False}