Why are functions used in C++ programming?

Functions in C++ programming are used primarily to organize code into reusable sections. This modular approach allows developers to write a piece of code once, encapsulate it within a function, and then call that function whenever needed without rewriting the code. This not only fosters code reusability but also enhances readability and maintainability. By dividing a program into smaller, clearly defined functions, programmers can manage complexity more effectively and isolate different functionalities, making it easier to debug and understand the overall structure of the code.

The other options, while they may have some relevance to programming in general, do not capture the primary purpose of functions as clearly as the concept of code organization and reusability does.