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Functions
Functions are the fundamental units of code organization, and they mark our first step from "writing scripts" to "writing engineering code." In this chapter, we start with function definition and invocation, focusing on the different parameter passing mechanisms—by value, by reference, and by pointer. Understanding the differences between them is a prerequisite for writing efficient code. We then look at how function overloading and default parameters work together, and finally, we explore inline and constexpr functions. These two keywords appear frequently in embedded and performance-sensitive scenarios.