Manolete Manolete - 1 month ago 7
C Question

Better alternatives for switch statements

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

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 < 1)) {
        return pointers[plane][direction];
    } else {
        return NULL;
    }
}
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