Question

class new_hashtable {
public:
    /* This is the datatype stored in the hashtable slots. */
    struct KEY_VALUE {
        KEY k;
        VALUE v;
        KEY_VALUE(const KEY &k_,const VALUE &v_) :k(k_), v(v_) {}
        KEY_VALUE() {}
    };
}

In above codes, is KEY_VALUE(const....) :k(k_), v(v_){} a copy constructor?? What does k(k_), v(v_) part do ?

Answer 1

The difference between class and struct in C++ is that the default for struct is public. Other than that they’re exactly the same.

So you have an inner class KEY_VALUE with all the members and methods public, with 2 constructors: the default, and one that receives 2 parameters. It is not a copy constructor. k(k_), v(v_) is the initialization list.