Functions in Python

Functions are a fundamental concept in Python. They allow you to organize your code into reusable blocks, making your programs cleaner and easier to manage. A function is a named section of a program that performs a specific task.

What is a Function?

A function in Python is defined using the def keyword followed by the function name, parentheses, and a colon. Inside the function, you write the code that you want the function to execute when called.

Example: Defining a Function

def greet():
    print("Hello, world!")

Explanation

In this example, we defined a function called greet(). When called, it will print "Hello, world!" to the screen. To call a function, simply write its name followed by parentheses, like this:

greet()

This will output:

Hello, world!

Functions with Parameters

Functions can also accept parameters, which are values that you pass into the function to modify its behavior. Here’s an example:

def greet(name):
    print("Hello, " + name + "!")

Now, the function greet() takes a parameter name. When you call the function, you can pass in a value:

greet("Alice")

This will output:

Hello, Alice!

Returning Values from Functions

Functions can also return values using the return keyword. This allows you to store the result of a function call in a variable for later use. Here’s an example:

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

result = add(3, 5)
print(result)

This will output:

8

Explanation

The function add() takes two parameters, a and b, and returns their sum. The return keyword sends the result back to the place where the function was called, and we store that result in the variable result.