C ++ keywords words are also called reserve words. The meaning of these words is already defined by the compiler.
For example int age =27; where int is the keyword whose special meaning is already defined. We cannot use it as an identifier. They always begin with the small latter.
List of all possible reserve words in C++ 2017
| Keywords (A-C) | Keywords (C-I) | Keywords (L-S) | Keywords (S-Z) |
| alignas | continue | long | static_cast |
| alignof | co_await | module | struct |
| and | co_return | mutable | switch |
| and_eq | co_yield | namespace | synchronized |
| asm | decltype | new | template |
| atomic_cancel | default | noexcept | this |
| atomic_commit | delete | not | thread_local |
| atomic_noexcept | do | not_eq | throw |
| auto | double | nullptr | true |
| bitand | dynamic_cast | operator | try |
| bitor | else | or | typedef |
| bool | enum | or_eq | typeid |
| break | explicit | private | typename |
| case | export | protected | union |
| catch | extern | public | unsigned |
| char | false | register | using |
| char16_t | float | reinterpret_cast | virtual |
| char32_t | for | requires | void |
| class | friend | return | volatile |
| compl | goto | short | wchar_t |
| concept | if | signed | while |
| const | import | sizeof | xor |
| constexpr | inline | static | xor_eq |
| const_cast | int | static_assert |