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Functions
Functions are the basic unit for organizing code, and they're also our first step from "writing scripts" to "writing real software." This chapter starts with function definition and invocation, then digs into the ways parameters can be passed—by value, by reference, and by const reference—since knowing how they differ is the prerequisite for writing efficient code. From there we look at how function overloading and default parameters work together, and finally we get to know inline and constexpr functions—two keywords that show up constantly in embedded and performance-sensitive scenarios.