You Plus C++ Plus Cocos2d-x - Cocos2d-x by Example Beginner's Guide - page 37

woIntegers , the compiler will replace it with the lines for the method declared in the
interface. So the inline method works just as statements inside a method; they do not
require their own bit of memory in the stack. But if you have a two-line inline method
called 50 times in your program, it means that the compiler will add a hundred lines to
your code.