Welcome to Python Functions
Functions are the cornerstone of well-structured, reusable, and readable code. In Python, a function is a named block of code that performs a specific task. You can pass data, known as parameters, into a function, and it can return data as a result.
Think of functions as mini-programs. Instead of writing the same block of code multiple times, you can define it once as a function and then “call” it whenever you need it. This principle is known as DRY (Don’t Repeat Yourself).
A function’s code only runs when it is called, not when it is defined. This allows you to set up complex logic that can be executed on demand.
Quick Demo: Your First Function
Let’s define a simple function called greet that returns a friendly message, and then call it to see the output.
Pyground
Define a greet function that returns 'Hello, PythonForAll!' and call it.
Expected Output:
Hello, PythonForAll!
Output:
Navigate the Guide
This section provides a deep dive into every aspect of defining and using functions in Python. Use the tabs below to explore each topic.
Anatomy of a Function
Dissect the fundamental structure of a Python function, including the def keyword, docstrings, the return statement, and the execution flow.
Functions are the most important organizational tool in Python. Investing time to master them will dramatically improve the quality and clarity of your code.