C++ :: Store Function To A Variable And Call It Using That Variable?

I want to store few different functions to a variable for different structs/classes and then call it later using that variable, is it possible? something like

struct item {
int ID;
int special; // for function
};

item Key;
Key.special = UseKey(KEY_KING);

// now when I want to call function "UseKey(KEY_KING)" I want to use "Key.special", like this

if(iCurrRoom == ROOM_KING)
Key.special;
else if(iCurrRoom == ROOM_DRAGON)
Fireball.special;