一次性写出C++中的所有关键字，有人会问了，到底有几个呢？ 下面来数数吧！
asm do if return try
auto double inline short typedef
bool dynamic_cast int signed typeid
break else long static union
case enum mutable static_cast unsigned
catch explicit namespace struct using
char export new switch virtual
class extern register sizeof typename
const false operator template void
const_cast float private this volatile
continue for protected throw wchar_t
default friend public true while
delete goto reinterpret_cast