6.1. Functions in Python: Introduction to Functions

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Functions in Python are one of the main building blocks when building larger and more complex applications. Functions provide a way to divide our code into useful blocks, allowing us to write it once, use it many times, and organize our code into logical blocks. This makes the code easier to understand, reuse, and maintain.

Introduction to Functions

In Python, a function is a group of related statements that perform a specific task. Functions help break our program into smaller, modular pieces. As our program becomes larger and more complex, functions make it more organized and manageable.

Also, it avoids repetition and makes the code reusable. Functions in Python provide the advantage of code reuse. We can define a function once and then we can call it anywhere in the program. It also helps to make the code more readable and organized.

Function Syntax

The syntax for defining a function in Python is:

def function_name(parameters):
    """docstring"""
    instructions

Here, 'def' is the keyword that tells Python that we are defining a function. Following 'def' is the name of the function, followed by parentheses which can house any parameters the function will take (more on that in a moment), and ending with a colon. Inside the function, we start with an optional docstring that describes what the function does. The docstring is a way to document a function so that other developers know what it does, without having to read the code. Following the docstring are the instructions the function will execute when called.

Calling a Function

Once we define the function, we can call it from our program using the function name followed by parentheses and any arguments the function requires. For example, if we have a function called 'greet' that takes a name as a parameter, we can call it like this:

greet('John')

Parameters and Arguments

Functions in Python can take arguments - values ​​that are passed to the function when it is called. Arguments are defined within the parentheses after the function name and can be referenced within the function by the parameter name. Parameters are the names that appear in a function definition, while arguments are the values ​​that are passed when the function is called.

Return Values

Functions in Python can return values. This is done using the 'return' keyword. When a function returns a value, the function can be used in expressions. The value that the function returns is called the return value.

In short, Python functions are a powerful way to organize code into logical, reusable blocks. They allow us to avoid code repetition, make our code more readable, and help us break down complex problems into smaller, more manageable pieces.

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286.2. Functions in Python: Function Definition