What is the simplest way to implement "weakness table" (usually in game)?

Question

For example, I have a game with some characters have 5 elements:fire,water,wood,light,dark.

the element has weakness which attack power will increase for some elements:

fire>wood

water>fire

wood>water

light>dark

dark>light

eg:

fire hit wood,the power is *2

fire hit water,the power is *0.5

I have a function to get the relation between element and factor:

float getFactor(string me,string enemy){
    if(me=="fire"){
        if(enemy=="fire"){
            return 1;
        }else if(enemy=="water"){
            return 0.5;
        }else if(enemy=="wood"){
            return 2;
        }else if(enemy=="light"){
            return 1;
        }else{
        return 1;
        }
    }else if(me=="water"){
        if(enemy=="fire"){
            return 2;
        }else if(enemy=="water"){
            return 1;
        }else if(enemy=="wood"){
            return 0.5;
        }else if(enemy=="light"){
            return 1;
        }else{
            return 1;
        }
    }else if(me=="wood"){
        if(enemy=="fire"){
            return 0.5;
        }else if(enemy=="water"){
            return 2;
        }else if(enemy=="wood"){
            return 1;
        }else if(enemy=="light"){
            return 1;
        }else{
            return 1;
        }
    }else if(me=="light"){
        if(enemy=="fire"){
            return 1;
        }else if(enemy=="water"){
            return 1;
        }else if(enemy=="wood"){
            return 1;
        }else if(enemy=="light"){
            return 1;
        }else{
            return 2;
        }
    }else{
        if(enemy=="fire"){
            return 1;
        }else if(enemy=="water"){
            return 1;
        }else if(enemy=="wood"){
            return 1;
        }else if(enemy=="light"){
            return 2;
        }else{
            return 1;
        }
    }
}

which getFactor("fire","water") will return 0.5;

this function works, but it has too much lines and too much if else statement,also it seems very hard to maintain if I add a new element to it.

is there any method to implement the table but in more maintainable code style and less line of codes?

Answer 1

In your development environment, can you use the STD?

If so, then perhaps a map may best suit you. http://www.cplusplus.com/reference/map/map/.

You can set as the map input a pair of elements (an enumerated int), and the attack factor as the output. You only need to define an output for the possible combinations.

Answer 2

If you want a table, use a table:

enum Elements { ELEM_FIRE, ELEM_WATER, ELEM_WOOD, ELEM_LIGHT, ELEM_DARK, NUM_ELEM };

float attack_factor[NUM_ELEM][NUM_ELEM] = {
    {1, .5f, 2, 1, 1}, // fire vs ...
    {2, 1, .5f, 1, 1}, // water vs ...
    ...
};

Now you just do

attack_factor[my_elem][enemy_elem]

to get the attack power. This approach requires that you store the element type as an enum value instead of as a string, but that's better coding style anyway for C++ since it limits the space of possible elements to the ones that are actually defined, and makes lots of functions really easy.

Another example of tables being useful:

const char *element_names[] = { "fire", "water", "wood", "light", "dark" };