c - Is it possible to have a linked list of different data types?

Question

This is just another interview question.

Can we have a linked list of different data types, i.e. each element in a linked list can have different structure or union elements? If it's possible can you please explain with an example?

Answer 1

Well in a linked list you don't HAVE to link like for like structs together. As long as they have the appropriate forward and/or backwards pointers you are fine. For example:

struct BaseLink
{
   BaseLink* pNext;
   BaseLink* pPrev;
   int       typeId;
};

struct StringLink
{
    BaseLink baseLink;
    char* pString;
};

struct IntLink
{
    BaseLink baseLink;
    int   nInt;
};

This way you'd have a linked list that goes from BaseLink to BaseLink. The extra data is not a problem. You want to see it as a StringLink? Then cast the BaseLink to a StringLink.

Just remember that you need some form of typeid in there so you know what to cast it to when you arrive at it.