在 C++ 中模板化列表

Question

I'm writing a program that needs a SkipList that I wrote a while back, but now I need it templated because it needs to use a custom class that I created. The problem I have is with creating the node in the List class. I use template <class t> on all my methods but I think that since both the node and the SkipList class use template <class t> , the same class t s interfere with each other or something.

In my SkipList.h, I have the method saying

Node <t>* createnode<t>(t,int);

And in the SkipList.cpp, the method says

template <class t>
Node<t>* SkipList<t>::createnode(t value, int level) {
    Node<t> *n = new Node<t>(value, level);
    return n;
}

This gives me an error in the.h file that says Template specialization requires 'template<>' , and when I add it in, it replaces the code to say

template<> Node<t>* createnode<t>(t,int);

But then my.cpp file says that there is no function definition anymore.

Does anyone know where I'm going wrong or what I'm missing? Thanks a ton for the help. My GitHub is here if anyone needs it for clarification

Answer 1

Few things to note:

• You can't define templates in .cpp files use headers .
• using namespace std; can and will lead to nasty things especially when included in a header like this.
• You shouldn't include bits/stdc++.h .

Now to address some things in the code. I am not sure if template <class t, class t> is valid, but at best it is useless in this case. Addressing your question: Yes the two class t s interfere with each other, but you don't need two different t s. You can't create a Node<t> with a t not matching the type of the List can you? Now even if you have a case where that is needed you can just use template <class T1, class T2> .

Now the fixed implementation would look like this:

template <class T>
class SkipList {
    int MAX_LEVEL;
    float p;
    Node<t>* header;
    int level;
public:
    SkipList<T>(int,float) { /* Include definition here */}
    int randomlevel() { /* Include definition here */}
    void insert(T) { /* Include definition here */}
    void remove(T) { /* Include definition here */}
    bool find(T) { /* Include definition here */}
    void print() { /* Include definition here */}
    Node<T>* createnode(T, int) { /* Include definition here */}
};

Similarly Node should be fixed as well (include the definition of the constructor).

An other thing you mentioned in your post is template specialisation. You can read about it here .

You also have a memory leak somewhere between your Node / SkipList classes. Consider moving to smart pointers.

Finally I strongly encourage that you go through the basics of C++ before you continue . You can't run before you can walk.