问题
Is there a way to perform compile-time function execution in C? With GCC? I've only seen this available using constexpr in C++.
回答1:
As long as there are only constants involved in an expression, it will get calculated at compile-time. C++ constexpr is mostly a type safe way of doing so without involving macros. In C, there are only macros. For example:
#define CIRCLE_AREA(r) (int32_t)( (double)(r) * (double)(r) * M_PI )
int32_t area = CIRCLE_AREA(5);
performs all calculations at compile-time, so it is equivalent to writing:
int32_t area = 78;
来源：https://stackoverflow.com/questions/36418757/compile-time-function-execution