Defining and Calling Functions
Explore how to create and invoke functions in Python to write reusable and modular code. Understand the difference between parameters and arguments, how to return values from functions, and the concept of local scope for variable management. This lesson enables you to build clear, efficient functions following best practices for naming and structure.
Repeating the same code in multiple places is a clear warning sign in programming. When we copy and paste logic, e.g., calculating a tax rate or formatting a user’s name, we increase the risk of errors. If that logic needs to change later, every duplicated instance must be found and updated, which is both time-consuming and error-prone.
Functions solve this problem by allowing us to give a name to a block of code and reuse it wherever it is needed. By encapsulating logic inside functions, we make our programs more modular, readable, and easier to maintain.
What are functions
In Python, a function is a named block of code that groups related instructions together. The code inside a function does not run immediately; instead, it runs only when the function is explicitly called.
We define a function using the def keyword, followed by the function’s name, parentheses, and a colon (:). The function’s body appears on the next line and is indented, just like the code inside conditionals and loops.
def <function_name>():# Function's body
Working with functions involves two steps: defining the function and calling it. A function must be defined before it can be called, since Python executes code from top to bottom.
We’ll begin with the simplest type of function: one that takes no input and produces ...