In C ++, there are two operators, the result of which can always be determined at compile time regardless of the operand (s), which are sizeof[1] and ::[2].
Of course, there are many specific uses of other operators that can be resolved at compile time, for example, those listed in the standard for integer constant expressions.
[1] C99, ++, . sizeof, VLA, . ++ VLA .
[2], , . , - .