Const ant Parameters

In the GetReflectedCopy example we passed an argument by reference and we were not planning to change it. We passed it only for convenience and speed. If you are not planning to modify the value it is safer to use const keyword. You can rewrite the function like this:

Point GetReflectedCopy ( const Point &From )

{

Point Result;

Result.dX = From.dY;

Result.dY = From.dX;

return Result;

}

The const keyword does not change the behavior of GetReflectedCopy but does make it safer – remember there are risks associated with pass by reference. If by accident you try to change its value, the compiler will complain and will not allow you to do this.

It is much easier to catch the problem when compiler complains rather than let GetReflectedCopy to change its argument by mistake and then debug the problem later.