names of variables, functions, user-defined types (structs and classes)
Rules of an identifier: enforced by compiler:
Exs. num1 best_score bestscore bestScore 3 different names main Main MAIN 3 different names. only main is special if If IF 3 different identifiers. Only if is keyword
Always use names that are as meaningful as possible to aid human understanding of the program. Program as communication between human and computer and between humans.
Compiler knows nothing about English or the world. It only knows what you tell it to do, it doesn't know your purpose or your intention.
Keywords: Need to be aware so that you don't try to create variables with these names
From C: auto break case char const continue default do double else enum extern float for goto if int long register return short signed sizeof static struct switch typedef union unsigned void volatile while C++ additions: asm catch class delete friend inline new operator private protected public template this throw try virtual ANSI C++ additions: bool false static_cast using const_cast mutable true wchar_t dynamic_cast namespace typeid explicit reinterpret_cast typenameNote that cin, cout, main are not keywords. But don't make variables with those names.
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