C++ Insights

Source:

template<typename T> struct Node {
    T data;
    Node * next = nullptr;
    Node(const T &data = T()) : data(data) {}
};

template<typename T> class MyLList {
    Node<T> * head = new Node<T>, *tail = head;
public:
    class MyIterator;
    using iterator = MyIterator;
    
    iterator begin() { return iterator(head->next); }
    iterator end()   { return iterator(nullptr); }

void insert_after(const T& value) {
        tail->next = new Node(value);
        tail = tail->next;
    }
};

template<typename T> class MyLList<T>::MyIterator {
    Node<T> * val;
public:
    MyIterator(Node<T> * val) : val(val) {}
    MyIterator& operator++() { 
        val = val->next;
        return *this;
    }
    bool operator!=(const MyIterator &it) {
        return val != it.val;
    }
    T& operator*() { return val->data; }
};

#include <algorithm>
#include <iostream>

int main() {
    MyLList<int> list;
    list.insert_after(3);
    list.insert_after(4);
    list.insert_after(6);
    list.insert_after(5);
    
    using std::cout;
    for (auto i : list)    cout << i << ' ';
    cout << '\n';

std::for_each(list.begin(), list.end(), [](int &x) { x *= 2; });
    for (auto i : list)    cout << i << ' ';

return 0;
}

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