Hands-On Embedded Programming with C++17

Function inlining

The inline keyword in C++ is a hint to the compiler to let it know that we would like each call to a function whose name is preceded by this keyword to result in that function's implementation instead of being copied to the location of the call, thus skipping the overhead of a function call.

This is a compile-time optimization, which only adds the size of the function implementation to the compiler output, once for each distinct call to the inline function.