Lesson 7: Functions and Modules | Coding Class Series

Introduction

Welcome to Lesson 7!
In this lesson, we will learn about functions and modules in Python. Functions allow you to reuse code, while modules help you organize your programs efficiently.

1. Functions

A function is a block of code that performs a specific task and can be reused multiple times.

Syntax:

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

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

Key Points:

• Functions start with the def keyword.
• Arguments can be passed inside parentheses.
• return keyword is used to give back a result.

Example with Return:

def add(a, b):
    return a + b

result = add(5, 3)
print(result)  # Output: 8

2. Modules

A module is a file containing Python definitions and functions.
You can import modules to use their functions in your program.

Importing a module:

import math

print(math.sqrt(16))  # Output: 4.0

From module import specific function:

from math import pow

print(pow(2, 3))  # Output: 8.0

Creating your own module:

1. Create a file my_module.py:

def welcome():
    print("Welcome to my module!")

2. Import in another file:

import my_module

my_module.welcome()  # Output: Welcome to my module!

3. Advantages of Functions and Modules

• Reusability: Write once, use multiple times.
• Organization: Keeps code clean and structured.
• Efficiency: Saves time and reduces errors.
• Scalability: Easier to maintain and expand large programs.

Practice Exercises

1. Create a function multiply(a, b) that returns the product of two numbers.
2. Write a function that takes a list of numbers and returns the largest number.
3. Create a module math_utils.py with a function square(n) that returns the square of a number. Import it and test.
4. Use the random module to generate 5 random numbers between 1 and 50.

Lesson 4: Functions and Modular Programming | Coding Class Series

Introduction

Welcome to Lesson 4!
In this lesson, we will learn about functions – reusable blocks of code – and how to organize your program into modules. Functions make your code cleaner, easier to read, and maintainable.

What is a Function?

A function is a block of code that performs a specific task. You can call it whenever you need to perform that task.

Example in Python:

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

greet("Alice")  # Output: Hello, Alice!
greet("Bob")    # Output: Hello, Bob!

Explanation:

• def greet(name): → defines a function named greet with a parameter name.
• print(f"Hello, {name}!") → code inside the function.
• greet("Alice") → calls the function with argument "Alice".

Benefits of Functions

1. Reusability: Write once, use many times.
2. Readability: Makes code organized and easier to understand.
3. Debugging: Easy to test and fix small blocks of code.

Modular Programming

Modular programming is the practice of splitting your code into multiple files or modules. Each module has a specific purpose, making your program scalable and easier to maintain.

Example:

• math_utils.py → contains functions for math operations
• main.py → calls functions from math_utils.py

# math_utils.py
def add(a, b):
    return a + b

def subtract(a, b):
    return a - b

# main.py
from math_utils import add, subtract

print(add(5, 3))      # Output: 8
print(subtract(5, 3)) # Output: 2

Practice Exercises

1. Write a function to calculate the factorial of a number.
2. Create a function to check if a string is a palindrome.
3. Write a module string_utils.py containing functions: reverse_string(), count_vowels().
4. Import the module in another file and test all the functions.