Pythonic Wonders: Chapter 3 - Functions and Modules

Intro

Functions and modules are essential tools for building complex programs in Python. Functions allow you to break up your code into reusable pieces, while modules enable you to organize your code into separate files.

Functions

A function is a block of code that performs a specific task. Functions can take input arguments and return output values. Here’s an example of a simple function:

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

greet("Alice")

In this example, the program defines a function called greet that takes a name argument and prints a personalized greeting.

Functions can also return values using the return keyword. Here’s an example:

def square(x):
    return x ** 2

result = square(3)
print(result)

In this example, the program defines a function called square that takes a number x and returns its square.

Modules

A module is a file containing Python code that can be imported into another program. Modules enable you to organize your code into separate files and reuse code across multiple programs.

Here’s an example of a simple module:

# mymodule.py

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

def square(x):
    return x ** 2

In this example, the program defines a module called mymodule that contains two functions: greet and square.

You can use the import keyword to import a module into your program. Here’s an example:

import mymodule

mymodule.greet("Alice")
result = mymodule.square(3)
print(result)

In this example, the program imports the mymodule module and uses its greet and square functions.

Standard Library

Python also comes with a standard library of modules that provide additional functionality. You can use the import keyword to import these modules into your program. Here’s an example:

import math

result = math.sqrt(9)
print(result)

In this example, the program imports the math module and uses its sqrt function to calculate the square root of 9.