Learn What Is Function? | What Is a Function in Python?

Prerequisites

Introduction to Python

Definition

In Python, a function is a named block of reusable code that performs a specific task. It is a fundamental concept in programming and plays a crucial role in organizing and structuring code. Functions are like building blocks in LEGO. They allow you to create reusable chunks of code that can be used in different parts of your program.

Using functions in Python is highly beneficial as they allow you to call the same block of code multiple times without rewriting it, saving time and reducing errors. Moreover, they help break down complex tasks into smaller, manageable steps, with each function performing a specific action, making the code more readable and easier to maintain.

In simpler terms, functions are like breaking down tasks into smaller pieces that you can use repeatedly. This approach makes your program more convenient to write, change, and understand.

Defining a Function

Define the simplest function in Python.

First, use the def keyword;
Next, specify the function name - a unique identifier that represents the function. It follows variables' naming conventions, such as using lowercase letters and underscores (this convention is called snake_case);
Use (): after the function name - in these brackets, specify the function's arguments (parameters);
Then, specify the function body with the indented new line;
After the function body, specify the return value of the function using different keywords such as return, assign, or yield;
Finally, use functions in code. To do so, call the function using its name and specifying its parameters.

Create a simple function that prints 'Hello, world!' in the console, and then call this function in the code.


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# Specify the function name
# The function doesn't require any parameters, so we simply use `():`
def print_hello():
    # Function body: we have to use indentation when defining it.
    print('Hello, world!')
    # The function doesn't return anything, so we don't need to write additional code

# Call the function
print_hello()

The print() function inside print_hello() is a built-in function that prints text to the console. It takes a string as an argument specified in the parentheses.

A function can perform an action, such as printing a message, without returning a value. The presence of a return statement depends on whether the function needs to produce an output that can be used elsewhere in the program.

The print_hello() function displays a string in the console, but you cannot use this string in the program or pass it to other functions. Therefore, the print_hello() function has no return value.

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Section 1. Chapter 1

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