Python Functions and Modules

by Mani · Published February 9, 2024 · Updated February 9, 2024

Python Functions

What are Functions?

Functions in Python are blocks of reusable code that perform a specific task. They allow you to break down your program into smaller, manageable pieces. Functions enhance code readability, promote reusability, and make your programs more organized.

Creating a Function

To define a function, use the def keyword followed by the function name and parentheses. You can also include parameters (inputs) inside the parentheses. Here’s a simple example:

def greet(): print("Hello, World!") # Call the function greet() print("Outside function")

In the above example:

We’ve created a function named greet().
When we call greet(), it prints “Hello, World!”.
The control then continues outside the function, and “Outside function” is printed.

Python Modules

What are Modules?

As your program grows, it may contain many lines of code. Instead of putting everything in a single file, you can use modules to separate code into separate files based on functionality. This keeps your code organized and easier to maintain.

A module is a file that contains code to perform a specific task. It can include variables, functions, classes, and more.

Creating a Module

Let’s create a simple module named example.py. Save the following code in a file named example.py:

# example.py def add(a, b): result = a + b return result

In this module, we’ve defined a function add() that takes two numbers and returns their sum.

Importing Modules

To use a module in your Python program, you need to import it. You can import your own user-defined modules or Python’s standard library modules.

Importing User-Defined Modules

Suppose you’ve created the example.py module. To import it, use the import keyword:

import example # Access the function using the dot operator result = example.add(4, 5) print("Sum:", result)

Importing Python Standard Library Modules

Python’s standard library contains over 200 modules. For example, to get the value of π (pi), you can import the math module:

import math # Use math.pi to get the value of pi print("The value of pi is", math.pi)

Renaming Modules

You can also rename modules for convenience:

import math as m

# Now use m.pi instead of math.pi
print("The value of pi is", m.pi)

Importing Specific Names

If you only need specific names from a module, use the from ... import statement:

from math import pi # Now you can directly use pi print("The value of pi is", pi)

Remember, importing everything with the asterisk (*) symbol is not recommended for good programming practice.

That’s it! You’ve discovered the power of Python functions and modules. They make your code cleaner, more reusable, and easier to maintain.

Python Functions and Modules