Functions

Defining Functions

def greet():
    print("Hello!")
greet()  # Hello!

Functions with Parameters

def greet(name):
    print(f"Hello, {name}!")
greet("John")  # Hello, John!

Default Parameters

def greet(name="Guest"):
    print(f"Hello, {name}!")
greet()        # Hello, Guest!
greet("John") # Hello, John!

Return Values

def add(a, b):
    return a + b
result = add(3, 5)
print(result)  # 8

Multiple Return Values

def calculate(a, b):
    return a + b, a - b, a * b
add, sub, mul = calculate(10, 5)
print(add, sub, mul)  # 15 5 50

args and *kwargs

# *args - variable positional arguments
def sum_all(*args):
    return sum(args)
print(sum_all(1, 2, 3, 4))  # 10
kwargs - variable keyword arguments
def print_info(kwargs):
    for key, value in kwargs.items():
        print(f"{key}: {value}")
print_info(name="John", age=30)
name: John
age: 30

Lambda Functions

# Anonymous function
square = lambda x: x  2
print(square(5))  # 25
With sorted
pairs = [(1, 'one'), (3, 'three'), (2, 'two')]
pairs.sort(key=lambda x: x[0])

Summary

• Functions: reusable code blocks
• Parameters: positional, default, args, *kwargs
• Return: single or multiple values
• Lambda: anonymous functions

Next Lesson

In the next lesson, you'll learn about modules and packages.