Function with Parameters

Parameters allow functions to accept input data and produce different outputs based on that input. They make functions flexible and reusable for various scenarios.

Function parameters (also called arguments) allow you to pass data into functions. This makes functions flexible and reusable with different inputs.

Parameter Syntax:

def function_name(parameter1, parameter2):

    # Use parameters in function body

    return result

Single Parameter:

def greet(name):

    return f"Hello, {name}!"


print(greet("Alice"))  # "Hello, Alice!"

print(greet("Bob"))    # "Hello, Bob!"

Multiple Parameters:

def add(a, b):

    return a + b


result = add(5, 3)  # 8

Parameter Types:

1. Positional Parameters (Order Matters):

def divide(a, b):

    return a / b


divide(10, 2)  # 5.0 (10 ÷ 2)

divide(2, 10)  # 0.2 (2 ÷ 10) - different result!

2. Default Parameters:

def greet(name="World"):

    return f"Hello, {name}!"


greet()         # "Hello, World!"

greet("Alice")  # "Hello, Alice!"

3. Keyword Arguments (Named):

def introduce(name, age):

    return f"{name} is {age} years old"


# Named arguments - order doesn't matter

introduce(age=25, name="Alice")

**4. *args - Variable Positional Arguments:**

def sum_all(*numbers):

    return sum(numbers)


sum_all(1, 2, 3)        # 6

sum_all(1, 2, 3, 4, 5)  # 15

5. kwargs - Variable Keyword Arguments:

def print_info(kwargs):

    for key, value in kwargs.items():

        print(f"{key}: {value}")


print_info(name="Alice", age=30, city="NYC")

Best Practices:

• Use descriptive parameter names


• Put default parameters after required ones


• Don't use mutable defaults (list, dict)


• Document expected parameter types

def greet(name: str) -> str:

    return f"Hello, {name}!"