C++ Dynamic list without quote unquote Linked List

List.cpp

#include <iostream>
//#include "List/List.h"


template <typename T>
class List {
private:
    T *data;
    T *tmp;
    int storage = 1;
    int used = 0;
    void add(T item) {
        this->data[this->used] = item;
        this->used++;
    }
public:
    //List() = default;
    List() {
        this->data = (T*)malloc(this->storage * sizeof(T));
    }
    void append(T item) {
        if (this->used == this->storage) {
            this->storage++;
            this->tmp = (T*)realloc(this->data, this->storage * sizeof(T));
            this->data = this->tmp;
            add(item);
        } else {
            add(item);
        }
    }
    int size() {
        return this->used;
    }
    int capacity() {
        return this->storage;
    }
    bool empty() {
        return this->used == 0;
    }
    ~List() {
        free(this->data);
        free(this->tmp);
        this->storage    = 0;
        this->used = 0;
    }
    void display() {
        for (int i = 0; i < used; i++) {
            std::cout << "item: " << this->data[i] << std::endl;
        }
    }
};
int main() {
    List<int> list;// = new List<int>();

    list.append(1);
    list.append(2);
    list.append(3);
    list.append(4);
    list.append(5);
    list.display();
    return 0;
}