However, I left out two items of interest. You must give the function definition physically before you call the function. You simply type in the entire definition of the function where you would normally put the prototype. Inline functions are not very important, but it is good to understand them. The basic idea is to save time at a cost in space.
Inline functions are a lot like a placeholder.
Once you define an inline function, using the 'inline' keyword, whenever you call that function the compiler will replace the function call with the actual code from the function. Simple, function calls are simply more time consuming than writing all of the code without functions. To go through your program and replace a function you have used 100 times with the code from the function would be time consuming. Of course, by using the inline function to replace the function calls with code you will also greatly increase the size of your program. Using the inline keyword is simple, just put it before the name of a function.