Better alternatives for switch statements

Question

I know that this has been already discussed, and there are multiple answers to it. See Performance of array of functions over if and switch statements for instance, however I would like to get some other ideas.

I've got a function with a large switch statement. This is 26 case and each with a "left" or "right" option. This function returns a pointer based on two given parameters (plane and direction):

double* getPointer(int plane, int direction) {
  switch (plane)
  {
  case 0:
    if (direction == 0)
      return  p_YZ_L; // Left
    else if (dir == 1)
      return p_YZ_R;  //Right
    else {
      return 0;
    }

    break;
    ...
  case 25:
    ...
  }
}

with

planes -> [0-25]
direction -> [0,1] 

I have been thinking on an array of functions, but this could also be tedious and I am not sure if it is the best option. Also it is not clear to me how to do it properly. Any ideas?

Answer 1

You can create a lookup table like this:

double *pointers[26][2] = {
    { p_YZ_L, p_YZ_R },
    ...
};

Then your function becomes much simpler:

double* getPointer(int plane, int direction) {
    if ((plane >= 0) && (plane < 26) && (direction >= 0) && (direction < 2)) {
        return pointers[plane][direction];
    } else {
        return NULL;
    }
}

Answer 2

If you are just tired of typing, yu can use the preprocessor, e.g.:

#define PLZ(dir) if(!dir)return(p_YZ_L);else if(dir==1)return(p_YZ_R);else return 0;