c++ - constexpr in C (or equivalent) -


i trying string-based switch expression work in c using hash function. i've been able work clean syntax using 'constexpr' clang/llvm turned c++, though code c.

however, there of course odd side effects of having compile c++, lack of void* implicit casting becomes awkward.

so question how solve dilemma (without slapping c11 committee upside head why wasn't added c spec)

  1. is there way constexpr option turned on c?
  2. is there way implicit void* casting turned on c++?
  3. is there clean way code in c11/c99 doesn't require recalculating hashes?

here current example code:

constexpr uint64 chash(char const* text, uint64 last_value = basis) {     return *str ? chash(text+1, (*text ^ last_value) * prime) : last_value; }  void switchfunction(char const* text) {     switch(hash(text))     {         case chash("first"):             break;         case chash("second"):             break;         case chash("third"):             break;         default:             break;     } }

is there way constexpr option turned on c?

no, no such thing exists in c.

is there way implicit void* casting turned on c++?

no, c++ has mandatory type safety of pointers.

is there clean way code in c11/c99 doesn't require recalculating hashes?

the way can it, traditional way macros. in case create function-like macro parameters, , use on compile-time constants, computations done @ compile-time. unfortunately, code turn rather ugly, there no way avoid in c.

the best way might prepare such compile-time parameters external script/program, store them raw data tables in c program.


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