Creating Reusable Functions

Functions encapsulate logic into reusable units, making code more organized and maintainable. Mastering functions is crucial for building complex programs.

Function Structure

def greet(name):
    """Returns personalized greeting"""
    return f"Hello, {name}!"
print(greet("Alice"))  # → Hello, Alice!
→
Hello, Alice!
Key components:
  • def keyword starts function definition
  • Parentheses contain parameters
  • Colon ends declaration line
  • Indented body block

Return Mechanism

def is_positive(n):
    return n > 0
print(is_positive(5))   # → True
print(is_positive(-3))  # → False
→
True\nFalse

Common Errors

# Forgetting return statement
def add(a, b):
    a + b  # No return → returns None
# Incorrect indentation
def wrong():
print("Oops")  # IndentationError

Practical Use: Password Checker

def is_strong(password):
    """Checks if password has ≥8 chars and numbers"""
    return len(password) >= 8 and any(c.isdigit() for c in password)
print(is_strong("pass123"))  # → True
print(is_strong("weak"))     # → False
→
True\nFalse

Your Task: Even Number Checker

Complete the is_even function:

  1. Take integer n as parameter
  2. Return True if even, False otherwise
  3. Test with numbers 1-5

Remember: Even numbers have no remainder when divided by 2.

Section 1/5Function Structure

Function Structure

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Creating Reusable Functions

Functions encapsulate logic into reusable units, making code more organized and maintainable. Mastering functions is crucial for building complex programs.

Function Structure

def greet(name):
    """Returns personalized greeting"""
    return f"Hello, {name}!"
print(greet("Alice"))  # → Hello, Alice!
→
Hello, Alice!
Key components:
  • def keyword starts function definition
  • Parentheses contain parameters
  • Colon ends declaration line
  • Indented body block

Output:

Click "Check" to run your code.