In C++ there are some really naughty keywords that you should ignore
auto, register, export.
auto and register are bad because you are probably not as clever as the compiler for doing micro scale optimisations. Compilers are really good at their job, and don't need to be told to make a variable exist mostly in a register for speed, nor do they need to be told that a local variable needs to be thrown away at the end of the function scope.
export however is hedious, and if you ever come across it, run away. export allows the body of a template to exist outside the declaration. This means that the template is no longer a fast typesafe macro system, but a generics system, which is a bad thing for speed. Avoid it.